Evolution of a Peat- Contemporaneous Channel: The Galatia Channel, Middle Pennsylvanian, of the Illinois Basin W. John Nelson,1 Scott D. Elrick,1 William A. DiMichele,2 and Philip R. Ames3 1Illinois State Geological Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign 2Smithsonian Institution, National Museum of Natural History, Washington, DC 3John T. Boyd Co., Denver, Colorado Herrin Coal Briar Hill Coal e ston MemberSt. e D sbu rg avi Lim Dyke r d Turner Mine Shale Dykersburg Member Springfield underclay Coal 0 0 Galatia channel Delafield PrecurPsorer cCuhrsaonrn Gelalatia channel Member (new) 5 20 GalatiaG aMlaetmiab Merember (new) 10 m estone 40 ftHanover Lim Excello Shale Houchin Creek Coal Circular 605 2020 ILLINOIS STATE GEOLOGICAL SURVEY Prairie Research Institute University of Illinois at Urbana-Champaign Front cover: Diagram showing units between the Houchin Creek and Herrin Coals, including members newly named in this report. © 2020 University of Illinois Board of Trustees. All rights reserved. For permissions information, contact the Illinois State Geological Survey. Evolution of a Peat- Contemporaneous Channel: The Galatia Channel, Middle Pennsylvanian, of the Illinois Basin W. John Nelson,1 Scott D. Elrick,1 William A. DiMichele,2 and Philip R. Ames3 1Illinois State Geological Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign 2Smithsonian Institution, National Museum of Natural History, Washington, DC 3John T. Boyd Co., Denver, Colorado Circular 605 2020 ILLINOIS STATE GEOLOGICAL SURVEY Prairie Research Institute University of Illinois at Urbana-Champaign 615 E. Peabody Drive Champaign, Illinois 61820-6918 http://www.isgs.illinois.edu Suggested citation: Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geologi- cal Survey, Circular 605, 85 p. Contents Abstract 1 Introduction 1 Geologic Setting 1 Previous Research 3 Crevasse-Splay Model 3 Cyclicity and Sequence Stratigraphy 5 Stratigraphy 5 Houchin Creek Coal 5 Excello Shale Member 7 Hanover Limestone Member 7 Delafield Member (New) 7 Name and Definition 7 Type Section 7 Thickness and Distribution 7 Lithology 8 Contacts 8 Fossils 9 Interpretation 10 Galatia Member (New) 10 Name and Definition 10 Type Section 12 Lithology 12 Contacts 12 Thickness and Distribution 12 Interpretation 12 Underclay of Springfield Coal 14 Springfield Coal 14 Thickness and Distribution 14 Shaly Coal Bordering the Channel 14 Relationship of Coal to the Channel 18 Dykersburg (Shale) Member 18 Definition 18 Thickness and Distribution 22 Lithology 22 Fossils 22 “Rolls” 22 Coal “Splits” 23 Major Disturbances in Coal 29 Absence of Natural Levees 33 Origin of the Dykersburg Member 33 Turner Mine Shale Member 35 St. David Limestone Member 36 Canton Shale 36 Briar Hill Coal 36 Summary 36 Other Channels Related to the Galatia Channel 37 Sullivan Channel 37 Effingham Channel 37 Leslie Cemetery Channel 41 Other Channels 47 Similar Channels Affecting Other Coal Seams 49 Colchester Coal and Francis Creek Shale 49 Herrin Coal, Energy Shale, and Walshville Channel 49 Baker Coal and Winslow-Henderson Channel 51 Danville Coal 54 Murphysboro Coal and Oraville Channel 55 Discussion 56 Model of Channel Development 56 Stage 1: Prograding Deltas During Early Regression 56 Stage 2: Valley Incision and Soil Development During Regression 59 Stage 3: Aggradation and Gleying During Late Regression 59 Stage 4: Peat Initiation and Paludification at Early Lowstand 59 Stage 5: Widespread Peat Accumulation at Lowstand 60 Stage 6: Peat Rafting and Splitting During Initial Transgression 60 Stage 7: Estuarine Flooding During Early Transgression 60 Stage 8: Estuary Advances Inland as Regression Continues 61 Stage 9: Black Shale of Late Transgression and Highstand 61 Stage 10: Limestone Deposition at Highstand to Early Regression 61 Linkage of Climate and Eustasy 61 Peat Developed at Lowstand 63 Rapid Transgression, Gradual Regression 63 Relationship of the Effingham and Galatia Channels 65 Channels and Cyclothems: A Summary Model 67 The “Typical” Cyclothem on a Cratonic Platform 70 Cyclothem Models Do not Address Contemporaneous Channels 71 The Gray-Shale Wedge and Its Relationship to the Channel 72 Conclusions 74 Acknowledgments 74 References 74 Appendix: Type and Reference Sections of Named Units 83 A. Principal Reference Section of the Houchin Creek Coal Member, Carbondale Formation 83 B. Type Section of the Hanover Limestone Member 83 C. Type Section of the Delafield Member (New) 84 D. Type Section of the Galatia Member (New) 85 Tables A1 Type section of the Delafield Member (new) 84 A2 Type section of the Galatia Member (new) 85 Figures 1 Map of the Illinois Basin showing the extent of Pennsylvanian rocks, thickness of the Springfield Coal, and channels interrupting the coal 2 2 Correlation chart showing the positions of key units within the Pennsylvanian Subsystem 4 3 Satellite image of the mouth of the Mississippi River showing natural levees and crevasse splays 5 4 Diagram showing units between the Houchin Creek and Herrin Coals, including members newly named in this report 6 5 Wireline log illustrating the typical response of key units 8 6 Graphic logs from cores serving as type sections of the newly named members 10 7 Isopach map of the Delafield Member 11 8 Map from Potter (1962) showing thickness (in feet) of sandstone between the Houchin Creek and Springfield Coals, with the Galatia channel superimposed 13 9 Photograph showing underclay of the Springfield Coal at American Coal’s Galatia Mine, Saline County, Illinois 15 10 Map showing the thickness and mined areas of the Springfield Coal throughout Illinois 16 11 Photographs showing thinly interlaminated shale and dull to bright coal along margins of the Galatia channel at the Prosperity Mine in Gibson County, Indiana 17 12 Cross section of the Galatia channel in American Coal’s Galatia Mine in Saline County, Illinois, based on core drilling and observations in the mine 19 13 Photographs showing the ragged, erosive contact between the light-colored siltstone of the Dykersburg Member and the underlying coaly shale of the Galatia Member in the channel crossing at the Galatia Mine, Saline County, Illinois 21 14 Map showing the thickness of the Dykersburg Member in the vicinity of the Galatia channel in southeastern Illinois 23 15 Photograph showing rhythmic lamination in sandy facies of the Dykersburg Member in American Coal’s Millennium Mine, Saline County, Illinois 24 16 Photograph showing rhythmic lamination in sandy facies of the Dykersburg Member in the Millennium Mine, with lamination offlapping the top of the coal 24 17 Photograph showing large, well-preserved fronds of fossil plant foliage (Laevenopteris?) in the Dykersburg Member at the Millennium Mine, Saline County, Illinois 25 18 Photograph of an upright tree stump, rooted at the top of the coal and encased in mudstone of the Dykersburg Member, at American Coal’s Galatia Mine in Saline County, Illinois 25 19 Photographs of “rolls” at the top of the Springfield Coal, filled with Dykersburg sediments, at American Coal’s Millennium Mine in Saline County, Illinois 26 20 Photographs showing the Springfield Coal “split” by massive siltstone in the Millennium Mine 27 21 Photographs of siltstone “splits” in the Springfield Coal 28 22 Profile view of the disturbance in Figure 21a in the Millennium Mine, Saline County, Illinois 29 23 Profile view of the disturbance in Figure 21b in the Millennium Mine 30 24 Map and cross section of the disturbance in the Sahara No. 20 Mine, Saline County, Illinois 31 25 Map and cross section of the disturbance in the Dering Coal Company No. 2 Mine, Saline County, Illinois 32 26 Drawings from Meier and Harper (1981) illustrating a major disruption of the Springfield Coal in AMAX Coal’s Wabash Mine in Wabash County, Illinois 34 27 (Top) Image of the major disturbance in the Wabash Mine. (Bottom) The same drawing with interpretation added, depicting the peat deposit torn asunder, with the upper part floated away from the lower. 35 28 Photograph of interlaminated carbonaceous shale and bright to dull coal close to the margin of the Sullivan channel in the Oaktown Mine in Knox County, Indiana 38 29 Photograph of interlaminated carbonaceous shale and bright to dull coal close to the margin of the Sullivan channel in the Carlisle Mine in Sullivan County, Indiana 39 30 Map from Potter (1962) showing the Effingham channel as described in this report 40 31 Gamma-ray–neutron log from the Berry Petroleum No. 11-14 Pitcher well in Jasper County, Illinois, indicating coal in the upper part of the Effingham channel fill 41 32 Graphic log of core from Richland County, Illinois, showing filling of the Effingham channel 42 33 Interpretive cross section of the Effingham channel in Richland County, Illinois, showing two stages of infilling, with local coal at the top of the lower stage 43 34 Maps of the Leslie Cemetery channel 43 35 Map of the Leslie Cemetery channel prepared for this study, using information from boreholes and mines 44 36 Generalized sketches illustrating opposite margins of the Leslie Cemetery channel, as exposed in surface mines in the eastern half of 9S, 4W, Warrick County, Indiana 45 37 Interpretive diagram showing sequential development of the Leslie Cemetery channel 46 38 Map and cross section of the Terre Haute channel 47 39 Map of the Illinois Basin showing channels and gray-shale wedges affecting the Murphysboro, Colchester, Herrin, Baker, and Danville Coals 48 40 Stratigraphic column showing the units mentioned in the section on channels affecting coal seams other than the Springfield 50 41 Isopach map of the Francis Creek Shale 51 42 Interpretive cross section of the Herrin Coal, Walshville channel, and Energy Shale 52 43 Map showing the Walshville channel and sulfur content of the Herrin Coal 53 44 Map showing the Winslow-Henderson channel 54 45 Interpretive cross section of the Winslow-Henderson channel 55 46 Disruption of the Danville Coal, with the seam “split” by a thick wedge of mudstone 56 47 Map showing the thickness of the Murphysboro Coal near the Oraville channel in Jackson and Perry Counties, southwestern Illinois 57 48 Interpretive cross section of the Oraville channel 58 49 Stage 1: Deposition of the Delafield Member as a series of coalescing deltas during the onset of a glacial stage as the sea level began to fall 59 50 Stage 2: Channel incision of delta sediments 60 51 Stage 3: The Galatia channel developed a meander belt 61 52 Stage 4: The change to a humid climate caused the Springfield peat to begin to form 62 53 Stage 5: Springfield peat accumulates across a large area of the basin 63 54 Stage 6: A warming climate brought rapid melting of the glaciers and a sea-level rise 64 55 Stage 7: Peat swamps drowned as the estuary became an embayment 65 56 Stage 8: As the transgression continued apace, the entire basin area was submerged in deep water, which became stratified and anoxic, and black mud (Turner Mine Shale) was deposited 66 57 Stage 9: Normal marine circulation resumed near the apex of an interglacial stage (marine highstand), bringing a brief interlude of carbonate sedimentation (St. David Limestone) 67 58 Stage 10: Marine regression begins the next cycle 68 59 Conceptual model of Pangea during a glacial episode of the Pennsylvanian 68 60 Conceptual model of Pangea during an interglacial episode of the Pennsylvanian 69 61 Diagram illustrating the possible relationship of the Effingham and Galatia channels to Midcontinent cyclothems 70 Plates 1 Map of the southeastern part of the Illinois Basin showing the thickness of the Springfield Coal, channels that affect the coal, and major structural features 2 Cross section of the Galatia channel in the Raleigh area, Saline County, Illinois 3 Cross section of the Galatia channel in Wabash County, Illinois 4 Cross section of the Effingham channel in the Olney area, Richland County, Illinois 5 Cross section of the Effingham channel in the Stewardson area, Shelby and Effingham Counties, Illinois 6 Cross section of the Leslie Cemetery channel, Warrick and Gibson Counties, Indiana ABSTRACT tidally influenced sediment shielded the Moreover, these thick, gray sediments peat from sulfur-rich marine water and are associated with paleochannels that For more than 40 years, geologists have sediment that invaded the area during existed during peat formation. Channels understood that the thickness and maximum transgression. Large-scale contemporaneous with the Herrin and quality of the Springfield Coal are inti- rafting of peat during the initial stage of Springfield Coals, the two most important mately related to the Galatia channel, transgression produced “splits” and large economic seams in the basin, have been a paleochannel that existed contempo- coal-seam disruptions. identified and mapped in detail. Similar raneously with peat deposition. Early relationships involving the Murphysboro, models envisioned a setting similar to the Other channels developed at the same Colchester, Baker, and Danville Coals also Mississippi delta, in which the river peri- time as the Galatia. The south-flowing have been documented (Treworgy and odically breached its natural levees and Sullivan channel in Indiana is probably Jacobson 1979). carried crevasse splays of gray mud (Dyk- an upstream segment of the Galatia. A ersburg Shale) into flanking peat swamps, large southeast-flowing system in east- Previous authors have explained these shielding peat from a later influx of sul- central Illinois, named the Effingham relationships by using a model based on fur-bearing marine water and sediment. channel, was abandoned before Spring- the modern Mississippi delta. They envi- Using new findings and reinterpreting old field peat formation. The Leslie Cemetery sioned a channel that periodically broke maps, we present a new model for Galatia channel in southern Indiana began as a through its natural levees and discharged channel development. Before the forma- precursor tributary to the Galatia channel sediment-laden water into flanking peat tion of Springfield peat, falling sea levels that was abandoned and then reoccupied swamps. The resulting “crevasse splays” exposed the Illinois Basin area to soil during later stages of peat formation. The created clastic “splits” within the peat development and fluvial incision under poorly understood Terre Haute channel along the channel margins. However, no a seasonal semiarid to wet subhumid may have a similar origin. natural levees have been found along climate. A “precursor” Galatia channel, the paleochannels, significant evidence carrying a bed load of sand, formed a Channels and gray-shale clastic wedges exists for tidal sedimentation, and further meander belt several miles (kilometers) similar to the Galatia channel and Dyk- research has shown that the Mississippi wide. Under a progressively more humid ersburg Shale affected the Murphysboro, delta is probably not a good analogue for climate at glacial maximum, vegetation Colchester, Herrin, Baker, and Danville Pennsylvanian coal deposits. Hence, the cover flourished and Springfield peat Coals. Each of these presents variations model needs revision. accumulation took place. As inferred on the theme, the Herrin example being under previous models, the thickest peat most similar to the Springfield. This study describes and explains the formed in lowlands flanking the chan- Galatia channel, one of the best-known We interpret coal (peat) as having formed nel. Dense, strongly rooted vegetation examples of a paleochannel contempo-during glacial maxima, when the sea level stabilized channel banks and restricted raneous with peat accumulation. Such was lowest and global cooling pinned the upstream sediment runoff. As a result, paleochannels yield key insights into intertropical convergence zone near the meanders became locked into place the ways eustasy and climate influence equator. The resulting ever-wet climate in and the Galatia became a “black-water” sedimentation, and they add complex-the tropics maintained the consistently stream that carried only fine suspended ity to generalized models of cyclic sedi-high water table required for the produc- sediment. Some of this sediment was car- mentation. A new model is presented tion and preservation of peat. A warming ried into peat swamps along the channel here, which takes in the complete history cycle brought deglaciation, rapid sea- margins, creating belts of shaly coal a few of development of the Galatia channel level rise, and a change to the seasonal hundred feet (meters) wide bordering the and the landscapes of which it was a wet–dry tropical climate, which in turn no-coal area. part. This model is then applied to other caused rapid drowning and burial of the paleochannels in the Illinois Basin, and At the end of the glacial episode, the sea peat deposit. likely can be applied in other basins. level rose, drowning the peat swamp The impact of the Galatia channel and its and turning the Galatia channel into a analogues on coal thickness and quality broad estuary flanked by mud flats. With Geologic Settinghas been understood since the 1960s. concurrent changes in atmospheric cir- Our new findings and model of origin for The Illinois Basin, also called the Eastern culation, the Illinois Basin climate shifted these channels provide insights into the Interior Basin, covers much of Illinois from year-round rainfall to a strongly driving forces behind sedimentary cycles along with southwestern Indiana and part seasonal, wet–dry (monsoonal) regime. overlooked by most previous authors. of western Kentucky in the east-central This drier climate led to reduced vegeta- United States (Figure 1). The Illinois Basin tion cover and increased soil erosion and is an interior cratonic basin that devel- runoff in the Galatia drainage basin. Thus, INTRODUCTION oped progressively throughout Paleo- the channel carried a heavy sediment zoic time (Leighton et al. 1991). During Since the late 1960s, geologists working load, largely silt and fine sand. Much of the Pennsylvanian Period, widespread in the Illinois Basin have recognized that this was deposited in the estuary as the tectonic deformation took place in the deposits of thick coal having a relatively Dykersburg Shale, which rapidly buried Illinois Basin in response to the Ances- low sulfur content (<2%) are associ- the Springfield peat to a depth of more tral Rocky Mountains orogeny (McBride ated with thick, nonmarine gray mud- than 98 ft (>30 m). As envisioned by ear- and Nelson 1998) and perhaps flexural stone and siltstone overlying the coal. lier geologists, this thick deposit of gray, interactions with the Allegheny orogeny Illinois State Geological Survey Circular 605 1 Illinois Indiana THICKNESS >66 inches 42–66 inches nel 28–42 inches han c <28 inches aala ti Coal split or thin G Channel Insufficient data Coal eroded or not deposited Extent of the Pennsylvanian System Kentucky 0 20 40 60 mi N 0 50 100 km Figure 1 Map of the Illinois Basin showing the extent of Pennsylvanian rocks, thickness of the Springfield Coal, and channels interrupting the coal. From Finley et al. (2005). Straight lines separating polygons are artifacts of mapping protocol in original. (Quinlan and Beaumont 1984). In Illinois, Previous Research • Gray silty shale (Dykersburg Shale the La Salle Anticlinorium, Du Quoin With their eyes on industrial develop- Member) directly overlies the coal Monocline, Salem and Louden Anticlines, ment, the scientists who made the first along the channel. and numerous smaller structures all were geological surveys of Illinois, Indiana, and • Where the Dykersburg is thicker than active during the Pennsylvanian. In fact, Kentucky paid special attention to coal 19.7 ft (6 m), the Springfield Coal has the Springfield Coal thins where it crosses deposits. David Dale Owen first described a lower than normal sulfur content the Louden Anticline and the southern what is now called the Springfield Coal in (2.5% or less). part of the La Salle Anticlinorium (Plate Indiana (1859) and in Kentucky (1856); Hopkins (1968) presented little geologic 1), evidence that these structures were Amos Worthen did the same in Illinois interpretation, aside from proposing that rising during peat accumulation. (1870). Gilbert H. Cady (1919, p. 21) may the channel existed during peat forma- On a global scale, assembly of the super- have been the first to remark on tion and that rapid burial by nonmarine continent of Pangaea was well underway a sandstone which occupies what gray mud (Dykersburg) shielded the peat by the Middle Pennsylvanian. Southwest seems to have been a channel running from sulfur-bearing marine water and of the Illinois Basin, plate collision had southward through the central part of sediments. closed off the Arkoma Basin, and the the district in the west side of Raleigh A series of reports (Gluskoter and Simon Ouachita Mountains were rising (House- and Harrisburg Townships (Ts. 8 and 1968; Gluskoter and Hopkins 1970; All- knecht 1983). Tectonic activity was wide- 9 S., R. 6 E.) [Saline County, Illinois]. gaier and Hopkins 1975; Hopkins et al. spread throughout the Midcontinent, This channel was apparently formed 1979; Jacobson 1983) rapidly followed, including the Illinois Basin (McBride and and filled before the deposition of No. augmenting Hopkins’s initial findings, Nelson 1998). Plate reconstructions show 6 coal and probably during or after the developing an interpretive model, and the Illinois Basin close to, or slightly south deposition of No. 5 coal. outlining similar relationships for areas of of, the equator (Scotese 2010; Blakey 2011). The extent of the channel north of Saline low-sulfur coal bordering paleochannels County in Illinois remained little known in other Illinois coal seams. Hopkins et al. The Springfield Coal Member1 of the because the greater depth of the coal (1979, p. 148) proposed the name “Galatia Carbondale Formation is of late Desmoi- deterred mining. Over the next 50 years, channel,” taking the name of a small com- nesian age (Figure 2), which is equiva- other authors briefly remarked on aspects munity near the feature in Saline County, lent to the Asturian (Westphalian D) of of what came to be known as the Galatia Illinois. Western Europe and to late Moscovian channel. Mining companies coped with In Indiana, Donald L. Eggert (1978) was on the global time scale (Davydov et al. channel-related features and recorded the first to recognize paleochannels con- 2012). It is informally known as No. 5 Coal them on their maps. But until 1968, these temporaneous with the Springfield Coal. in Illinois, Coal V in Indiana, and No. 9 features were known only as isolated phe- A series of follow-up papers and reports Coal in western Kentucky. The Spring- nomena. (Eggert 1982, 1984, 1994; Eggert and field is correlative with the Summit Coal Adams 1985) described the Galatia chan- of the Western Interior Basin and with Hopkins’s (1968) report on resources the Middle Kittanning coal bed of the of the Springfield Coal made a break- nel and related features in Gibson, Pike, and Warrick Counties. Together, these northern Appalachian Basin on the basis through. Using mainly electric logs from oil test holes, Hopkins mapped the coal articles described relationships closely of physical stratigraphy (Wanless 1939), similar to those developed in Illinois, palynology of the coal (Peppers 1996), in areas where no mining or coal explo- ration had taken place. Hopkins also and they relied on the same interpretive and conodonts (Heckel 2009) and ammo- noids (Work et al. 2009) in associated employed the Illinois State Geological crevasse-splay model. marine rocks. Survey’s extensive database of coal qual- ity analyses. His key findings remain Crevasse-Splay Model The Springfield accounts for about 29% essentially valid today: of remaining identified Illinois Basin Models applying modern deltaic pro-• Clastic rocks replace the Springfield resources and has been the most exten- cesses to ancient rocks (e.g., Morgan Coal along a southwest-trending, sively mined coal seam in the Illinois and Shaver 1970) were in vogue when meandering tract across southeastern Basin (Hatch and Affolter 2002). The coal the Galatia channel was first recognized. Illinois, averaging about 0.6 mi (1 km) is high-volatile bituminous in rank and Being close at hand and thoroughly wide. Hopkins (1968, p. 1) character- generally is bright-banded, having well- investigated, the Mississippi delta com-ized this feature (then unnamed) as a developed cleat and lacking significant manded the attention of American geolo-channel “believed to be in part con- clastic partings. Thickness varies from gists. Explicitly or otherwise, authors temporaneous with the coal.” about 3.9 to 4.9 ft (1.2 to 1.5 m) in most had the Mississippi delta in mind as • Coal is abnormally thin or “split” with areas where the coal has been mined. they explained coal-contemporaneous layers of rock close to channel mar- Thicker coal, locally exceeding 9.8 ft (3 channels in the Illinois Basin. Leading gins. m), is confined to the flanks of the Galatia the way were Johnson (1972) and All-• The thickest coal occurs close to the channel. gaier and Hopkins (1975). Hopkins et al. channel. (1979) referred to the Dykersburg and 1Classification differs among the three state geological surveys. Indiana and Illinois regard the Springfield as a formal member, whereas Kentucky classifies all coals informally as beds. 3 Epoch/Age (Stage) LithostratigraphyIllinois Basin Global NorthAmerica Formation Graphic Member 295 hiatus Asselian Nealian ? Mauzy 300 Gzhelian Virgilian Mattoon 305 Missourian BondKasimovian Patoka Shelburn Danville Coal Herrin Coal Springfield Coal Desmoinesian Carbondale Houchin Creek C. 310 Colchester Coal Davis Coal Moscovian Murphysboro Coal 315 Tradewater Atokan Bashkirian 320 Caseyville Morrowan hiatus Miss. Serpukhovian Chesterian 325 Ma Figure 2 Correlation chart showing the positions of key units within the Pennsylvanian Subsystem. Global and provincial stage boundaries and ages in millions of years (Ma) are after Gradstein et al. (2012). Energy Shales as crevasse-splay deposits (Figure 3). Nelson et al. (1987, p. 12–14) continued to interpret the origin of the derived from those channels. Summariz- departed slightly from previous scenarios, Energy Shale in terms of deltaic crevasse ing earlier work, Nelson (1983, figure 8) noting the lack of evidence for natural splays. illustrated Galatia channel environments, levees while continuing to place the coal including levees, crevasse splays, and a and shale deposits within an overall del- Eggert (1982) and Eggert and Adams bird-foot delta like that of the Mississippi taic setting. Similarly, Burk et al. (1987) (1985) also explicitly related channel 4 Circular 605 Illinois State Geological Survey CARBONIFEROUS PERMIAN SYSTEM Pennsylvanian Subsystem In the past 40 years, sequence stratig- raphers have generated an immense Natural levee amount of literature accompanied by Crevasse splay a maze of terminology. A brief review revealed that different authors apply some of the same terms with different meanings. Ironically, sequence stratig- raphy has yet to see much usage in its original homeland, the Illinois Basin. Full application of sequence concepts Distributary to Pennsylvanian rocks in this basin is channel beyond the scope of this report. Never- Interdistributary theless, we wish to discuss rocks related bay to the Springfield Coal and Galatia chan- nel in terms of their interpreted position in eustatic cycles. To avoid misunder- standing, we are using terms in the fol- lowing fashion: Lowstand: an episode when sea level was at its lowest, corresponding to the maximum extent of continental gla- ciers. Figure 3 Satellite image of the mouth of the Mississippi River showing natural levees and crevasse splays. Fron Earthstar Geographic SIO, © 2020. Transgression: an episode when sea level was rising in response to the melt- ing of continental glaciers (deglacia- development in Indiana to the modern the term “cyclothem” based mainly on tion). Mississippi delta. They envisioned the work in western Illinois. By this time, Highstand: an episode when sea level Galatia and associated channels as del- other workers had recognized Pennsyl- was highest, correlating to the maxi- taic distributaries flanked by natural vanian cycles elsewhere in the United mum deglaciation. levees that frequently failed, spilling States. Among the driving mechanisms sediment-laden water into adjoining suggested were interrupted subsidence, Regression: an episode of falling sea peat swamps. Eggert (1994) regarded the tectonic movements, and autogenic level related to the growth of continen- Galatia channel as part of a delta that processes such as channel avulsion and tal glaciers. prograded seaward during peat deposi- delta switching (Langenheim and Nelson tion (p. 14) and alluded to the Dykersburg 1992). Wanless and Shepard (1935, 1936) STRATIGRAPHY Shale as lacustrine and overbank mud were the first to propose glacially driven This section describes, in ascending (p. 16). eustatic changes of sea level as the driv- order, the rock units that enclose the ing process. Archer and Kvale (1993) and Archer et Springfield Coal and Galatia paleochan- al. (1994, 1995) represent the first major Sequence stratigraphy came into use nel (Figure 4). To facilitate discussion of departure from the deltaic model in the within the oil industry in the 1970s and the new depositional model, two new Illinois Basin. These authors recognized reached the broader geologic community members are proposed. rhythmic lamination and other tidal sig- with American Association of Petroleum natures in Illinois gray shale associated Geologists’ Memoir 26 (Payton 1977). Houchin Creek Coal with low-sulfur coal. Thus, they placed However, Sloss et al. (1949), who worked deposits such as the Dykersburg Shale in Illinois, are acknowledged as pioneers. Although the Houchin Creek Coal is into estuarine environments rather than Basically, a sequence is an updated thick enough to mine only in small areas, fluvially dominated deltas. version of the cyclothem, with glacial it is one of the most laterally extensive eustasy viewed as the primary causative coal members in the Illinois Basin. With Cyclicity and Sequence mechanism. A sequence is “a relatively rare exceptions, the Houchin Creek is a conformable succession of genetically single layer of bright-banded coal lack- Stratigraphy related strata bounded at its top and base ing significant clastic layers and resting on well-developed underclay. Pyrite The Illinois Basin is the birthplace of the by unconformities or their correlative cyclothem. Udden (1912) recognized four conformities” (Mitchum 1977, p. 210) and content is normally 3% or higher. Thick- ness varies from a streak to as much as cycles of deposition in Middle Pennsylva- represents a single cycle of sea-level rise nian rocks near Peoria, Illinois; the oldest and fall. Modern sequence stratigraphers 5.9 ft (1.8 m), but coal thicker than 3.9 cycle included Coal No. 5 (Springfield). recognize as many as five orders or levels ft (1.2 m) is exceptional, and the usual Weller (1930) introduced “cyclical forma- of cyclicity and relate them to periodic thickness range is 7.9 to 23.6 in. (20 to changes in the earth’s climate caused by 60 cm). The coal occurs throughout the tions”; Wanless and Weller (1932) coined astronomical processes. Illinois State Geological Survey Circular 605 5 nel han Trun k c 6 Herrin Coal Briar Hill Coal e imes ton St. Dav L Dyker sburg Member id Turner Mine Shale Dykersburg Member Springfield underclay Coal 0 0 Galatia channel Delafield PrecurPsorer cCuhrsaonrn Gelalatia channel Member (new) 5 20 GalatiaG aMlaetmiab Merember (new) 10 m estone 40 ftHanover Lim Excello Shale Houchin Creek Coal Figure 4 Diagram showing units between the Houchin Creek and Herrin Coals, including members newly named in this report. Illinois Basin, except in a few small areas culation or agitation by waves and cur- Bottom waters were intermittently agi- of nondeposition near the northern and rents. Without taking account of eustasy, tated, likely below the normal wave base western margins and in other small areas Zangerl and Richardson (1963) advocated but within the storm wave base. Parts of where the coal was eroded in paleochan- deposition of black shale in shallow the basin may have been too deep for nels. With the overlying Excello Shale and lagoons having floating mats of algae that carbonate production. Thicker and purer Hanover Limestone, the Houchin Creek impeded circulation. In contrast, Heckel carbonate accumulated in shallower forms a package that is readily identified (1977) placed black shale deposition water on the Western Shelf. We interpret on nearly all types of well logs. A double- during highstand under starved-basin limestone deposition as occurring around peaked, or “bird’s beak,” profile is charac- conditions in water deep enough (330 highstand under a relatively dry, seasonal teristic on resistivity logs (Figure 5a). The ft [100 m]) that wind-driven circulation climate. Conversely, the switch from Houchin Creek evidently represents an in did not affect bottom waters. We favor black shale to limestone might reflect situ peat deposit that developed on a vir- Heckel’s model, but noting that he placed stronger wind-driven circulation under tually flat, tectonically stable coastal plain peat formation during transgression, climate otherwise unchanged (Cecil et al. of great extent. we suggest that black shale developed 2003b). during transgression to early highstand. Excello Shale Member Transgression was rapid (Archer et al., 2016) and often heralded by erosion Delafield Member (New) The Excello Shale is the black, slaty, phos- or “ravinement” (Gastaldo et al. 1993). Name and Definition phatic shale that overlies the Houchin Sedimentation slowed and water circula- Between the Hanover Limestone and the Creek/Mulky Coal across the Illinois and tion ceased in steadily deepening water. base of the Springfield Coal is a thick, Midcontinent Basins. This member is Peat on the sea floor consumed oxygen regionally extensive interval of shale, typical among Middle and Upper Penn- and contributed a great deal of carbon to siltstone, sandstone, and mudstone that sylvanian black “sheety” phosphatic shale bottom sediments. Rivers may have deliv- typically coarsens upward. The name units of the Illinois and Western Interior ered additional carbon, carrying plant Delafield Member is hereby proposed in Basins. It is hard, highly fissile, and well matter into the sea (James and Baker reference to the community of Delafield jointed, with a density lower than normal 1972; Banerjee et al. 2010; Holterhoff and in Hamilton County, southern Illinois. for shale because of a carbon content as Cassady 2012). high as 18.5%. Phosphatic laminae and bands of small lenses are common, as are Type Section large (to 3.3 ft [~1 m]) spheroidal dolo- Hanover Limestone Member The type section of the Delafield Member mite concretions. The upper part of the The marine limestone member that is the core from the Energy Plus ME-13 Excello tends to be mottled, burrowed, directly overlies the Excello Shale is called borehole, which was drilled about 1.6 mi and calcareous, grading into overlying the Hanover Limestone. The Hanover is (2.5 km) southeast of Delafield (sec. 31, limestone. Near its depositional limits on regionally continuous but locally lenticu- T4S, R6E, Hamilton County, county no. the western and northern basin margins, lar. In the deeper part of the basin, the 25463). The member occupies the depth black sheety shale gives way to mottled Hanover ranges from fossiliferous shale interval from 1,048.3 to 1,123.2 ft (319.5 to gray, green, and olive mudstone that is a few inches (centimeters) thick to lime- 342.4 m) in the core and is 74.9 ft (22.8 m) weakly fissile (James and Baker 1972). stone averaging around 9.8 in. (25 cm) thick (Figure 6 and Appendix, part C). The The Excello carries a highly restricted and rarely exceeding 19.7 in. (50 cm). The entire core from the Energy Plus borehole marine fauna of inarticulate brachiopods, usual lithology is dark gray, very argil- is in permanent storage at the Illinois ammonoids, bivalves, fish remains, and laceous, fossiliferous lime mudstone and State Geological Survey (ISGS) Samples conodonts. Articulate brachiopods have wackestone. Fossils are chiefly brachio- Library. The core description, a gamma- been found in their carbonate concre- pods and echinoderm fragments, along ray–density log, and other data on the tions (Wanless 1957, 1958). Burrows with a few gastropods, bivalves, bryozo- borehole are on file at the ISGS Geologic are rare, except near the upper contact. ans, and ostracods. Shells are commonly Records Unit and available via the ISGS Like other black phosphatic shales, the unbroken and crinoid stems are partly website. Excello produces very high (typically articulated, indicating low depositional off-scale) inflections on gamma-ray logs energy. The rock may be massive or show Thickness and Distribution (Figure 5b). Thickness varies from a few indistinct, wavy banding of fossil frag- centimeters to about 8.2 ft (2.5 m), with ments and shale laminae. On the western Weiner (1961) produced a map show- no regional trends evident. The Excello side of the basin, the Hanover tends to be ing the thickness of what is essentially is nearly coextensive with the Houchin thicker (locally >9.8 ft [3 m]) and the rock the Delafield Member in the Illinois Creek Coal. The lower contact is sharp is lighter colored, is less argillaceous, and Basin. Wanless et al. (1963, figure 13) and and shows evidence of erosion; in some contains more diverse fossils. The contact Wanless et al. (1970, figure 4) published cores, the coal is absent and the Excello with the Excello Shale may be sharp and more legible versions. As reproduced rests directly on underclay. wavy or gradational. here (Figure 7), the map shows that the Delafield Member thins westward from Black shale such as the Excello clearly The Hanover and its fauna record a return maximum values of more than 98.4 ft was deposited in marine water under to normal marine water circulation, with (>30 m) in southwestern Indiana and anoxic reducing conditions, lacking cir- near-normal salinity and oxygen content. southeastern Illinois. The greatest known Illinois State Geological Survey Circular 605 7 a Spontaneous PoStePntial Resistivity B H Sp Han. HC SV MQ C Figure 5 Wireline log illustrating the typical response of key units. (a) Electric log of Carter Oil No. 1 Beers well in sec. 28, T8S, R4E, Williamson County, Illinois (county no. 2107). B, Brereton Limestone; H, Herrin Coal; Sp, Springfield Coal; Han, Hanover Limestone; HC, Houchin Creek Coal; SV, Survant Coal; MQ, Mecca Quarry Shale; C, Colchester Coal. (b) Gamma-ray–resistivity log of Peabody Natural Gas No. 2 Short, in sec. 14, T7S, R7E, Hamilton County (county no. 25375). Figure continues on p. 9. thickness is 124.7 ft (38 m) in eastern bands of siderite is at the base. This (Springfield underclay). The upward- Wayne County, Illinois. The Delafield grades upward through silty shale to coarsening profile is evident on electric thins to less than 16.4 ft (<5 m) in much siltstone and fine-grained sandstone. and other geophysical logs (Figure 5). of western and northern Illinois, although Shale, siltstone, and sandstone are the detailed pattern undoubtedly is more commonly interlaminated in the upper Contacts complex than shown in Figure 7. Delafield. Structures include planar, wavy, ripple, and cross-lamination, The base of the Delafield Member is the Lithology along with slumped lamination. Definite top of the Hanover Limestone or, where neap–spring tidal bundles were displayed the Hanover is absent, the top of the The Delafield consistently coarsens in one of the cores examined. At the top, Excello Shale. This contact is sharp or gra- upward. Dark gray, sideritic clay-shale siltstone grades upward to claystone or dational within an interval a few centime- that contains abundant nodules and silty mudstone having paleosol features ters thick. The top of the Delafield is the 8 Circular 605 Illinois State Geological Survey b Gamma Ray Resistivity Brereton Ls. Anna Shale Herrin Coal St. David Ls. Turner Mine Shale Springfield C. Hanover Ls. Excello Shale Houchin Creek Coal Survant Coal Mecca Quarry Shale Davis Coal Figure 5 Continued. base of the Springfield Coal or the base Fossils Above this are found rare pectenoid of the new Galatia Member. The contact Fossils are scarce in the Delafield pelecypods, linguloid brachiopods, a to the coal is generally conformable but Member, but they record a transition single nautiloid cephalopod, and plant sharp, whereas the contact to the Galatia from near-normal marine conditions at fragments. Burrows are present but not Member is erosive. Where the Galatia the outset of deposition to increasingly common. The type core contains the Member is absent, the underclay of the brackish water through time. Articulate trace fossils Teichichnus and Conostichus, Springfield Coal is part of the Delafield brachiopods, crinoid fragments, and which have marine affinities. Member. other marine forms occur at the base. Illinois State Geological Survey Circular 605 9 a b Depth (ft) Depth (ft) Canton Shale St. David Limestone Turner Mine Shale Dykersburg Shale 1,050 700 Dykerburg Shale Delafield Member 1,100 750 Galatia Member Hanover Limestone Houchin Exce Creek Coal llo Shale 790 Total depth 788.0’ 1,150 Figure 6 Graphic logs from cores serving as type sections of the newly named members: (a) Energy Plus borehole no. ME-13 in sec. 31, T4S, R6E, type section of the Delafield Member. (b) Kerr-McGee borehole no. 7629-16 in sec. 29, T7S, R6E, Saline County, type section of the Galatia Member. Interpretation gave way to brackish water. At the end of Galatia Member (New) The Delafield reflects a rapidly prograd- Delafield deposition, terrestrial clastics essentially filled the Illinois Basin as mar- Name and Definitioning shoreline. Deposition apparently took place in a complex of deltas and shoal- ginal marine sedimentation gave way to Hopkins et al. (1979) named the Gala- ing bays; normal marine salinity rapidly emergence and soil formation (underclay tia channel, but the strata that fill the of Springfield Coal). channel have not been formally named. 1 0 Circular 605 Illinois State Geological Survey al Co fie ld g pri n S WISCONSIN IOWA ILLINOIS INDIANA KY IN MISSOURI THICKNESS (ft) 0–25 25–50 KY 50–75 75–100 KENTUCKY >100 ARKANSAS TENNESSEE 0 20 40 60 mi N 0 50 100 km Figure 7 Isopach map of the Delafield Member. After Wanless et al. (1970). Thicknesses are in feet. 11 Having a name for these rocks simplifies Type Section in well logs. Lacking lithologic evidence, discussion of the geology. Fortunately, As a type section, the core from Kerr- the contact may be mapped at the eleva- the name “Galatia” is available and is McGee borehole no. 7629-16 is hereby tion of the top of the coal adjacent to the hereby selected. The member takes its selected. The hole was drilled about 4.0 channel. name from the town of Galatia in Saline mi (6.5 km) northeast of Galatia in sec. County, Illinois, which is situated directly 29, T7S, R6E, Saline County (county no. Thickness and Distribution above the Galatia channel. 26537). Core from 7629-16 was logged Maps by Potter (1962, 1963), published In this report, the Galatia Member of the by ISGS geologists and is stored in its before the Galatia channel was recog- Carbondale Formation is considered entirety at the ISGS Samples Library in nized, portray the thickness of sandstone to comprise all rocks that fill channels Champaign (storage number C-14933). between the Springfield and Houchin that cut downward from near the top of Complete logs and other data for this hole Creek Coals (Figure 8). The sandstone the Delafield Member into older strata. are filed in the ISGS Geologic Records that Potter mapped is largely the Galatia These rocks are largely sandstone but Unit and are available via the ISGS web- Member of this report. Potter’s 1962 map also include siltstone, shale, heterolithic site. The Galatia Member in the type core covers southeastern Illinois at a scale of strata, and stringers of coal. Mapping extends from a depth of 745.4 to 786.0 ft about 1:250,000, whereas his 1963 map discloses that the Galatia channel of (227.2 to 240.0 m), making the unit 40.6 includes parts of Indiana and Kentucky Hopkins et al. (1979) is only one element ft (12.4 m) thick (Figure 6 and Appendix, at a smaller scale. An independently in a network of paleochannels or incised part D). prepared map by Wanless et al. (1970, valleys that traverse a large area of the Illi- figure 6) shows a closely similar pattern nois Basin. Most of these channels were Lithology of sandstone distribution. In addition, abandoned and filled prior to Springfield The Galatia Member is an upward-fining Hopkins (1968, plate 2) published two peat accumulation, but the Galatia chan- succession, commonly 65 to 100 ft (20 to cross sections of the Galatia channel. Our nel itself remained as an open waterway 30 m) thick (Figure 6). The lower part is own cross sections (Plates 2 and 3) show throughout the time of peat formation. dominantly sandstone. As seen in cores, similar relationships. Thus, the Galatia Member is largely older the sandstone is very fine to fine grained, than the Springfield Coal, but the upper Maps portray elongate bodies of sand-locally medium grained, overall fining part of the member is contemporaneous stone having looping, arcuate boundaries upward. Cross-bedding in the lower part with the coal within the Galatia channel. and forming a dendritic pattern. Cross gives way upward to rippled, wavy, and Remaining unchanged is the Dykersburg sections illustrate broad sand-filled chan-contorted or slumped laminations. Layers Shale Member (Hopkins 1968), which nels or valleys that were eroded from near of shale–pebble conglomerate occur in comprises gray shale, siltstone, and sand- the top of the Delafield Member. These the lower part. Also present are pebbles stone lying above the Springfield Coal valleys have steep sides and broad, nearly and fragments of siderite and stringers and beneath the black Turner Mine Shale. flat bottoms.of coal. Upper channel filling consists of Ledvina (1988, p. 638–646) used the name laminated to massive siltstone and silty Interpretation “Galatia Sandstone Member” for sand- shale or mudstone containing carbona- stone within the Galatia channel and also ceous flakes and scattered plant frag- Maps and sections portray a series of for lenses or tongues of sandstone within ments. Several cores showed rhythmic actively meandering, laterally migrat- the Dykersburg Shale. However, because lamination, with probable neap–spring ing fluvial channels. Superimposed onto Ledvina’s work was never published, it tidal cycles, near the top of the member. Potter’s map of sandstone thickness, the did not enter the U.S. Geological Survey The uppermost part of the Galatia Galatia channel of Hopkins (1968) coin- stratigraphic lexicon, so it does not con- Member, lateral to the Springfield Coal, cides with a large, southwest-trending flict with our definition of the Galatia is largely dark, carbonaceous shale and sandstone meander belt (Figure 8). Member. Lenses of sandstone within the claystone containing numerous ragged Therefore, this meander belt appears Dykersburg are here considered simply layers and stringers of coal. to have been a direct precursor to the part of the Dykersburg. Eggert (1982) Galatia channel that flowed through the named the fill of a paleochannel that Contacts Springfield peat swamp. The Galatia pre- splits the Springfield Coal in Indiana the cursor channel is the work of a river that The lower contact is erosive, cutting into Folsomville Member. As used by Eggert, flowed across the emerging coastal plain the Delafield Member and locally into the Folsomville is entirely within the prior to peat accumulation. Eroding soft older units, including the Houchin Creek Springfield Coal, whereas our Galatia sediments on a low gradient, this river Coal. This erosive basal contact is readily Member is both older than and con- freely meandered and carried a large sed-apparent in cores and in most geophysi- temporaneous with the Springfield. In iment load, derived partly from upland cal logs. The upper contact with the Dyk- addition, Eggert’s Folsomville Member sources and partly from recycling its own ersburg Shale is at least locally erosive, is restricted to a single paleochannel, the banks and bed. A broad, sandy meander as shown by drill cores and underground Leslie Cemetery channel. Thus, the Fol- belt was rapidly established. Through exposures in the now-abandoned Galatia somville and Galatia Members are sepa- time, the valley aggraded and stream Mine. Because upper Galatia and Dyk- rate entities. The Leslie Cemetery channel energy declined, reducing the sediment ersburg Members contain similar rock is discussed at greater length in a later load. Tidal influence became evident in types, this contact can be difficult to pick section of this report. the late stage of channel filling. 12 Circular 605 Illinois State Geological Survey 13 WAYNE WWAABBAASSHH EEDDWWAARRDDSS JEFFERSON HHAAMMIILLTTOONN SANDSTONE THICKNESS (ft) WWHHIITTEE 0 1–20 FFRRAANNKKLLIINN 21–40 41–80 81–160 GaClahtaian cnheanl nel WWIILLLLIIAAMMSSOONN SALINE GALLATIN N 0 5 10 mi 0 5 10 km Figure 8 Map from Potter (1962) showing the thickness (in feet) of sandstone between the Houchin Creek and Springfield Coals, with the Galatia channel (from Hopkins 1968) superimposed. Underclay of Springfield Coal zone of organic-rich shale, suggesting the Tectonic influence on coal thickness is Like most coal beds in the Illinois Basin, development of clastic swamps prior to evident. Not only the coal, but also the the Springfield normally is underlain the onset of peat formation. interval between the Springfield and by nonfissile mudstone that miners call Herrin Coals thins abruptly when cross-Because the area away from the channel underclay. Features such as roots, slick- ing the Du Quoin Monocline from east was topographically higher and better ensides, microscopic structures, and to west. The Springfield also thins mark-drained, soils developed during the entire secondary carbonate nodules demon- edly across the Louden Anticline and La interval of time while the Galatia precur- strate that the underclay is a paleosol, the Salle Anticlinorium, but not the Salem sor channel was being eroded and back- product of overprinting by soil develop- Anticline.filled. Calcite nodules and caliche layers ment in previously deposited sediment. require a subhumid to semiarid climate, Focusing on the Galatia channel, coal A paleosol is not a lithostratigraphic unit. strongly seasonal with distinct wet and thicker than 5.5 ft (1.7 m) closely cor- From the stratigraphic point of view, the dry seasons (Cecil and Dulong 2003). In responds to the limits of the precursor Springfield underclay is considered part contrast, soil formation within the Galatia channel (Figure 10 and Plate 1). The of the Delafield Member except close to meander belt was frequently interrupted floodplain atop the old meander belt the Galatia channel, where the underclay by lateral channel shifts. This low-lying, clearly was conducive to forming and is part of the Galatia Member. poorly drained, and frequently disturbed preserving peat. It is likely that peat for- Where the underclay is part of the area did not permit long-term pedogene- mation commenced earlier on this flood- Delafield Member, it is generally 4.9 to 9.8 sis or caliche development. The youngest plain than on adjacent higher ground. ft (1.5 to 3 m) thick and in places reaches landscape, along the riverbanks, saw little 13.1 ft (4 m). Black, organic-rich claystone or no soil development. Two narrow, sinuous belts of thick coal that intersect the main belt from the commonly occurs at the top. The remain- northwest in Hamilton County (Plate 1) der is olive-gray to greenish-gray clay- Springfield Coal probably represent small tributaries that stone that grades downward to siltstone Thickness and Distribution joined the precursor channel. Potter’s or silty mudstone (Figure 9). All except 1962 and 1963 maps do not show these the uppermost 1.0 to 2.0 ft (0.3 to 0.6 m) is Many authors have mapped this major features because Potter mapped sand- generally calcareous and contains irregu- coal deposit. Comprehensive reports by stone thickness, not channels. lar nodules of limestone or dolomite. A Treworgy and Bargh (1984) and Treworgy solid layer of carbonate rock as thick as et al. (2000) include statewide maps at Hopkins (1968) mapped several areas of 3.3 ft (1 m) occurs in places. This is micro- 1:500,000 scale. Hatch and Affolter (2002) “thin and split” coal flanking the Galatia granular, argillaceous to silty, and lacks published (in digital form) a Springfield channel. Details of these areas are rather fossils other than root traces. The lower thickness map that covers the entire Illi- elusive because mines do not enter them part of the paleosol is commonly riddled nois Basin. and few cores have been drilled. One area with irregular vertical fractures lined where core drilling confirms abnormally with siderite, calcite, and dolomite. These Two large regions of thick Springfield thin coal is east of the channel in T8S, soils have characteristics of Calcisols and Coal have been mapped (Figure 10). The R6E, Saline County. Here, coal progres- Vertisols. larger of the two covers nearly all of the sively thins from the edges inward and Fairfield Basin in Illinois, along with prac- is absent or reduced to isolated stringers Where underclay belongs to the Galatia tically all of Indiana and western Ken- in the center. As the coal thins, the upper Member, it is rarely thicker than 3.3 ft (1 tucky within the coal outcrop. The coal is part becomes shaly, grading into gray m) thick and less strongly developed than 39.4 in. (100 cm) or thicker across about shale above. Another such area, in west- in the Delafield Member. Root traces, 80% of this region, and it is consistently ern White County (Figure 10), has the slickensides, and granules or nodules 47.2 to 59.1 in. (120 to 150 cm) across arcuate shape of an oxbow lake. of siderite are present, but carbonate large areas. The thickest coal, locally nodules are rare and the rock is not cal- exceeding 118.1 in. (300 cm), is found These observations suggest that thin coal careous. In places close to the Galatia close to the margins of the Galatia chan- near the channel represents low-lying channel, no paleosol is present, and the nel. Coal thicker than 70.9 in. (180 cm) areas where standing water inhibited Springfield Coal grades downward to flanks the channel almost continuously in plant growth and peat production. Many laminated, carbonaceous shale. Such both Indiana and Illinois. such areas probably were meanders soils have characteristics of Protosols. abandoned shortly before the onset of The second area of thick coal encom- peat accumulation. The Springfield underclay exhibits a com- passes the part of north-central Illinois plex climatic history. Detailed examina- roughly bounded by Springfield, Decatur, tion (Rosenau et al. 2013) indicates that Bloomington, and Peoria. Where it has Shaly Coal Bordering the Channel the soil formed mostly under a seasonally been mined, the coal is generally 4 to 6 ft Bordering the entire length of the Galatia dry climatic regime, leading to vertic fea- (1.2 to 1.8 cm) thick. The coal is thinner channel on both sides are belts of shaly tures. Late in its history, the soil under- than 11.8 in. (30 cm) on most of the West- coal several hundred feet (meters) wide. went pronounced gleying, suggesting a ern Shelf except for a small area near the These exhibit a gradual lateral transi- change toward a much wetter climate. In outcrop in Perry and Randolph Counties tion from coal without clastic layers to places, the top of the paleosol grades into (Figure 10). interlaminated coal and shale (Figure the base of the coal through a transitional 11). Clastic layers steadily increase in 14 Circular 605 Illinois State Geological Survey Figure 9 Photograph showing underclay of the Springfield Coal at American Coal’s Galatia Mine, Saline County, Illinois. Field of view approximately 5 ft (1.5 m) square. number and thickness toward the chan- Cady (1919, p. 51) wrote of the old Galatia possibly as much as 10 feet [300 cm]. nel, although details differ from one place Colliery, This shale contains a large amount to another. The lower 6 inches to nearly 3 feet [15 of organic material, and impressions to 90 cm] of the coal contains layers of leaves and stems are exceedingly At American Coal’s Galatia Mine, shale of carbonaceous shale or “bone” that numerous in the roof of the entries. laminae first appear at the top of the render that part of the bed unmarket- seam. When approaching the channel, Similar conditions were encountered able. The middle of the bed is generally more and more shale layers appear, elsewhere in Saline County along both fairly clean for a thickness of 3 to 5 feet reducing the height of salable coal. Near margins of the channel. Mines where [90 to 150 cm]. The upper part of the the channel border is less than 1.6 ft (<0.5 shaly coal was encountered during the bed is again interbedded with shale, m) of shale-free coal at the base of the early to middle 20th century include the the partings increasing in number and seam, resting on underclay. Shale lami- Galatia Colliery, Peabody No. 47, Sahara thickness to the top of the bed, which nae are dark gray to black and loaded No. 16, and Sahara No. 14 west of the in this mine is about 6 feet [180 cm] with carbonized plant remains, grading channel and Peabody No. 43 and Sahara thick. The actual position of the top of to dull or “bone” coal alternating with No. 9 east of the channel. Several cored the bed is rather difficult to ascertain vitrain (bright coal) in laminae a few mil- test holes also record shaly coal fring- because stringers of coal apparently limeters thick. Lamination is highly tabu- ing the channel. In most cases, the shale leading out from the coal bed can be lar, and the transition from bright coal to partings are most numerous at the top of traced to as much as 5 or 6 feet [150 to dull coal to shale is very gradual. the seam, but in some places, they occur 180 cm] above the coal, and in places Illinois State Geological Survey Circular 605 15 nne l ha atia c l Ga Springfield Coal thickness (inches) 0 20 40 60 mi >66 Insufficent data N0 50 100 km 42 to 66 Sandstone channel; no coal 28 to 42 Mined-out areas; Springfield Coal 0 to 28 Springfield Coal eroded; no coal Figure 10 Map showing the thickness and mined areas of the Springfield Coal throughout Illinois. After Treworgy et al. (1999). Straight lines separating polygons are artifacts of mapping protocol in original. 0 0 30 1.0 cm ft 0 0 30 1.0 cm ft Figure 11 Photographs showing thinly interlaminated shale and dull to bright coal along margins of the Galatia channel at the Prosperity Mine in Gibson County, Indiana. The lower frame is a closer view of the upper. The ruler is graduated in 0.1-ft intervals 17 in the lower part as well. Where records about 0.6 mi (1 km) wide and describes and sandstone. Together, these findings are available, shaly coal rested on typical a series of broad, simple, open mean- indicate that during the time of peat for- underclay (ISGS field notes, open files). ders without significant cross-cutting of mation, the Galatia river carried mostly meanders or abandoned meanders (Plate (and possibly only) clay, rafted bits of The transition from coal to shale at chan- 1). The lack of complexity indicates that peat and vegetation, and finely dispersed nel’s edge was formerly well exposed the river did not migrate laterally while the organic matter. This light sediment in the Prosperity Mine of the Five Star peat was forming or subsequent to peat load contrasts with the heavy bed load of Mining Company in Pike County, Indi- formation. Evidently, interlocking roots sand in the “precursor” channel prior to ana. In one area within 1,000 ft (300 m) of growing plants and tough, matted peat peat formation. Thus, the Galatia during of the channel, the seam was more than stabilized its banks. The river course, the time of peat accumulation may have 10 ft (3 m) thick and shale laminae were which freely migrated before peat began been a “black-water stream” similar to confined to the uppermost 8 in. (20 to form, was locked into place throughout many found in modern ever-wet, densely cm). In another area of the mine, shale the time of Springfield peat accumula- vegetated tropical wetlands (Cecil et al. laminae appeared first near the base of tion. In a similar fashion, modern domed 2003a, 2003b). Modern black-water rivers the seam and made a vertical transition peat deposits have partially encroached are restricted to regions having an ever- between the weakly fissile, rooted shale on an infilled valley that was incised wet or perhumid climate, meaning that below through shaly coal to the normal during Late Pleistocene lowstand on rainfall exceeds evapotranspiration the coal above. The shaly zone thickened the Rajang River delta of Sarawak, East year around. Such a climate promotes gradually toward the channel. Malaysia. One distributary, the Lassa, lush vegetation growth, which stabilizes Belts of shaly coal record constant infil- has been abandoned and overtopped the landscape and inhibits soil erosion. tration of water bearing fine suspended with peat. Maps of coastal Sarawak show In contrast, soil erosion and the fluvial sediment into the peat swamp bordering river bends, and in some cases individual sediment load peak under a monsoonal the open-water channel. It is interesting meanders “locked” into place by peat regime having prolonged alternating that in the more than half a century since deposits (Staub and Esterle 1993, 1994; wet and dry seasons. A long annual Hopkins (1968) proposed the crevasse- Staub and Gastaldo 2003). dry season leaves much of the ground splay model, no natural levees have been unprotected from severe gullying during Previous authors generally depicted the found. The margins of the channel have the rainy season (Cecil 1990; Staub and Galatia channel as filled with sandstone. been densely core-drilled because of Esterle 1993, 1994; Staub and Gastaldo Drill holes that penetrate the channel the thick low-sulfur coal adjacent to the 2003; Cecil and Dulong 2003; Cecil et al. encounter a variety of clastic rocks, rang- channel and for engineering design in 2003a). Therefore, climate change from ing from shale and claystone to siltstone, underground mines. During our exten- a seasonally dry or monsoonal regime sandstone, and conglomerate. Because sive studies in active mines and those to ever-wet conditions likely heralded the Springfield is absent, ascertaining by other geologists, no levee facies have Springfield peat formation.which part of the channel-fill was depos- been encountered in cores anywhere ited while peat formed is not easy. By far, along the length of the channel. Being the best record is from the Galatia under- Dykersburg (Shale) Member subaerial features, natural levees would ground mine in Saline County, Illinois. To display intensive rooting, burrowing, and Definitionfacilitate underground haulage and ven- probably evidence of weathering. Clastic tilation, the company drove a set of mine Hopkins (1968) assigned the name Dyk- layers within and above the Springfield entries, or “headings,” completely across ersburg Shale (Figure 4) to the unit of gray Coal do not contain such features. There- the channel. A detailed profile (Figure 12) clastic strata that lies between the Spring- fore, we surmise that vegetation flour- is based on exposures in these headings, field Coal and Turner Mine Shale. As dis- ished in standing water up to the margins combined with closely spaced cores that cussed here, the Dykersburg comprises of the flowing Galatia river. A buffer zone were drilled to plan the channel crossing. a variety of rock types, ranging from true of clastic (non-peat-accumulating) wet- In the heart of the channel, rhythmically fissile shale to weakly fissile, laminated, lands lay between the channel and the laminated siltstone to very fine sandstone and massive mudstone, siltstone, and peat. The plants and their interlocking of the Dykersburg Member rests on dark, sandstone. On this basis, the name “Dyk- roots filtered out fine clastic sediment carbonaceous shale and claystone of the ersburg Member” seems more appropri- derived from the channel. In addition, Galatia Member with an erosional con- ate than “Dykersburg Shale.” However, changes in acidity from peat mire through tact. Near the north end of the crossing, the latter term has been used by nearly all clastic wetlands to the active channel may the carbonaceous shale and claystone previous authors. have caused clays to flocculate along the grade laterally into shaly Springfield Coal. channel margin rather than in the peat Chronologically, the Dykersburg is The erosive contact between Dykersburg itself, following a model that has been younger than the Springfield Coal, and siltstone and Galatia dark shale was proposed for other low-ash, low-sulfur it is younger than the Galatia Member observed both in the mine and in drill coal deposits (Staub and Cohen 1979). and the channels it fills. Cores and expo-cores (Figure 13). sures in underground mines show the Dykersburg in erosive contact with the Relationship of Coal to the Channel These observations are consistent with the fact that along the entire length of Galatia Member. However, the Galatia The path of the Galatia channel where the the Galatia, the coal intergrades with and Dykersburg Members contain similar Springfield Coal is missing is consistently shale or claystone rather than siltstone rock types and are difficult to distinguish 18 Circular 605 Illinois State Geological Survey SOUTH NORTH 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Datum --- Top of Herrin Coal Herrin Coal Briar Hill Coal equivalent TR TR TR TR TR TR TR TR Springfield Coal 15 m 50 ft Springfield Coal TR TR TR TR 1,000 ft Coal Siltstone or shale and Drill hole sandstone interlaminated 0 Shaly coal Shaly sanstone Excello Shale 0 300 m Cored Underclay Sandstone Limestone Fossil plants Interval fining upward Shale Upright stumps Black shale TR Tidal rhythmites Interval coarsening upward Figure 12 Cross section of the Galatia channel in American Coal’s Galatia Mine in Saline County, Illinois, based on core drilling and observations in the mine. 19 8 Figure 13 Photographs showing the ragged, erosive contact between the light- colored siltstone of the Dykersburg Member and the underlying coaly shale of the Galatia Member in the channel crossing at the Galatia Mine, Saline County, Illinois. (a) View of the east wall of the entry. Coaly shale of the Galatia Member grades laterally northward (left, out of view) to shaly Springfield Coal. The pick is approxi- mately 2 ft (60 cm) long. (b) Close-up view on the west wall of the entry. The heart of the Galatia channel is south (left) of view. Notice how erosion undercut the clay below layers of tough, fibrous peat. 21 in well logs other than cores. In addition, fined to the basal part of the Dykersburg, preserved in the basal layers near the wedges of Dykersburg locally split the in contact with the Springfield Coal. Galatia channel, where the Dykersburg Springfield Coal and separate the coal is thickest. Fossils are preserved as com- from its underclay. This is a seeming par- Regular bands, nodules, and small con- pressions; that is, they are carbonized or adox—a younger unit within and beneath cretions of siderite are common in finer coalified and stand out against the gray an older one. The unusual processes that grained facies of the Dykersburg. Small shale matrix (Figure 17). In many areas caused this anomaly are addressed later pyrite nodules occur in dark, carbona- near the channel, fossil tree stumps occur in this report. ceous shale, especially near the base of in growth position (Figure 18). Invariably, the member. these are rooted in the top of the Spring- Thickness and Distribution Sedimentary structures are mostly small field Coal. Rare Stigmaria roots, with The Dykersburg is closely associated with scale. Planar, wavy, ripple, flaser, and rootlets attached, have been found in the cross-lamination are most common. plant-rich basal part of the shale, sug-the Galatia channel. As mapped by Hop- gesting that a few trees were able to grow kins (1968) and Eggert (1994), the Dyk- Small load casts, ball-and-pillow struc- tures, and deformed or contorted lamina- during the initial stages of Dykersburg ersburg occupies an irregular southwest- trending belt along the Galatia channel tion (soft-sediment deformation) also are deposition. (Figure 14). This belt widens from about 9 commonly seen. No cross-bedding in sets The only invertebrate fossils are the to 12 mi (15 to 20 km) in Indiana to nearly thicker than a few centimeters has been inarticulate brachiopod Lingula and pec- 31 mi (50 km) in southern Illinois. Distri- encountered. tenoid pelecypods, such as Dunbarella. bution of the shale relative to the chan- Much of the lamination in the Dykers- Indicative of brackish water, these forms nel is not symmetrical. Most of the thick burg is strongly rhythmic. Specifically, occur chiefly on the outer margins of the shale is southeast of the channel in Indi- bundles of thin clay-rich laminae alter- Dykersburg. Trace fossils are uncom- ana, whereas thick shale in southern Illi- nate with bundles of thicker silt- or sand- mon. The few examples we have seen are nois is largely northwest of the channel. rich laminae (Figures 15 and 16). This mostly from cores, in the upper part of In places, the Dykersburg is missing right style of lamination is diagnostic of tidal the member. They are mostly vertical and up to the channel margin. Maximum settings with neap and spring tidal cycles inclined burrows, some such as Teichich- thickness of the Dykersburg increases (Archer and Kvale 1993; Archer et al. nus with gutter stacking. Horizontal bur- from about 15 mi (24 m) in Indiana to as 1994, 1995). We have observed examples rows are rare; no trails or feeding traces much as 24 mi (38 m) in Saline County, of tidal rhythmites through most of the have been observed. Root traces are non- Illinois. geographic extent of the Dykersburg and existent, except at the top of the Dykers- Beyond areas of thick, continuous Dyk- at various levels in vertical profiles of the burg directly beneath the Briar Hill Coal. ersburg, the member occurs as isolated unit. The only places where rhythmites pods and lenses that are typically 3.3 to are not developed are at the thin edges “Rolls” 9.8 ft (1 to 3 m) thick and several tens of of the Dykersburg, where the member is Miners apply the term “rolls” to bodies feet (meters) to roughly 328.1 ft (100 m) reduced to isolated lenses. of shale, siltstone, and sandstone at or across. These are known mostly from Large-scale (feet) inclined bedding has near the top of a coal seam. Rolls filled exposures in underground mines. Includ- been encountered in underground mines with Dykersburg Shale are prevalent ing these lenses, the width of the Dykers- close to the Galatia channel. Bedding of close to the Galatia channel, where the burg tract is 49.7 to 55.9 mi (80 to 90 km) the Dykersburg intersects the top of the Dykersburg is thick and relatively coarse along the southern outcrop. The extent of coal at angles as steep as 30°, although grained (siltstone, interlaminated shale, Dykersburg lenses farther north is poorly 15° to 20° is more usual (Figure 16). Such and sandstone). They are filled with rock known because less underground mining a structure signifies the lateral accretion identical to that overlying the coal at the has taken place there. of wedges of sediment. same site. In map view, rolls are elongate and straight to sinuous and are locally Lithology Although sandstone occurs mostly in the branching. Rolls commonly occur in par- upper part of the Dykersburg, it locally allel sets or swarms. In cross section, they Medium to medium-dark gray silty mud- is found directly on the Springfield Coal. are roughly lens shaped, with “riders” stone and fine- to coarse-grained silt- Sandstone bodies are lens shaped in or stringers of coal overlapping one or stone are the most prevalent rock types. cross section. Their lower contacts are both margins (Figure 19). Widths range Mudstone generally shows bedding or erosive, truncating underlying shale and from 3 to 30 ft (0.9 to 9 m), lengths from lamination but is weakly to moderately forming “rolls” in the coal (see below). tens to hundreds of feet (meters). Similar fissile. Much of the siltstone is nearly Some sandstone bodies are convex rolls disrupt the Herrin Coal elsewhere massive. Sandstone becomes common upward, grading laterally to siltstone and in west-central and southern Illinois where the Dykersburg is thickest. The mudstone. (Krausse et al. 1979; Bauer and DeMaris sandstone is light gray and very fine 1982; Nelson 1983; DiMichele et al. 2007). to fine grained, occurring as laminae, lenses, interbeds, and larger lens-shaped Fossils Rolls evidently formed during the early bodies. Volumetrically minor, dark gray Fossil land plants are widely distrib- stages of drowning and burial of the peat fissile clay-shale (no silt) is mostly con- uted. They are profuse and beautifully deposit. At least some rolls appear to have 22 Circular 605 Illinois State Geological Survey Black shale/limestone Dykersburg 20 ft+ Dykersburg <20 ft Galatia channel 0 20 40 mi N 0 50 km Figure 14 Map showing the thickness of the Dykersburg Member in the vicinity of the Galatia channel in south- eastern Illinois. After Treworgy et al. (1999). formed as tidal channels within the mud Coal “Splits” Markedly different are large splits in flats that developed along the flanks of Miners use the term “split” for a tabular which the Dykersburg Member intrudes drowning estuaries (e.g., DiMichele et al. or wedge-shaped layer of rock within a into the Springfield Coal. These splits 2007; Elrick et al. 2013). Currents scoured coal seam. Several types of splits occur are elongate lenses and tapering wedges the peat, which, although tough and in the Illinois Basin and have different of clastic rock that divide the coal along fibrous, was pliable and partially buoyant. modes of origin. Discussed previously bedding planes. Thickness ranges from Layers of peat were ripped out and clastic are the thin layers of dark shale that are a feather-edge to more than 30 ft (9 m), sediment filled the resulting voids. After interlayered with the Springfield Coal at with a lateral extent of up to several hun- burial, the roll filling compacted less than the margins of the Galatia channel. These dred feet (meters) in some cases. The the surrounding peat, so the roll assumed simply represent sediment that washed lithology of splits closely resembles that a lens shape. into the peat swamp. of the Dykersburg Member overlying the Illinois State Geological Survey Circular 605 23 neap } month spring Approximately 1 m Figure 15 Photograph showing rhythmic lamination in sandy facies of the Dykersburg Member in American Coal’s Millennium Mine, Saline County, Illinois. Enlarged view at right. Reprinted from Palaeogeography, Palaeoclimatology, Palaeoecology, v. 487, p. 74, W.A. DiMichele, S.D. Elrick, and W.J. Nelson, Vegetational zonation in a swamp forest, Middle Pennsylvanian, Illinois Basin, U.S.A., indicates niche differentiation in a wetland plant com- munity. Copyright 2017, with permission from Elsevier. Figure 16 Photograph showing rhythmic lamination in sandy facies of the Dykersburg 24 Member in the Millennium Mine, with lamination offlapping the top of the coal. Sediment thus was deposited in a wedge, prograding from left to right. Figure 17 Photograph showing large, well-preserved fronds of fossil plant foliage (Laevenopteris?) in the Dykersburg Member at the Millennium Mine, Saline County, Illinois. Figure 18 Photograph of an upright tree stump, rooted at the top of the coal and encased in mudstone of the D ykersburg Member, at American Coal’s Galatia Mine in Saline County, Illinois. 25 Figure 19 Photograph of “rolls” at the top of the Springfield Coal, filled with Dykersburg sediments, at American Coal’s Millennium Mine in Saline County, Illinois. Ragged splaying of coal layers at the margins of rolls evokes fibrous peat layers ripped out by strong currents. coal at the same locality. Most prevalent diagonally from the upper to the lower plant remains to be preserved in the is medium gray, silty mudstone and silt- layer of coal (Figure 21). Splits of the type lower part of the split, as they are in the stone, but some splits consist of very fine described here commonly occur hun- basal Dykersburg at the top of the Spring- sandstone. The rock may be massive, or dreds of feet (meters) to more than 0.6 mi field seam. Moreover, when plant growth it may display indistinct horizontal to (>1 km) away from the Galatia channel resumed above the split, roots should mildly contorted layering. Well-defined and are surrounded by “normal” coal so have penetrated the latter. The absence of tidal lamination is rarely (if ever) seen. that the splits lack a direct connection to stumps, plant remains, roots, and other the channel. soil features casts doubt on splits being A number of features of these splits are crevasse splays. noteworthy and significant in interpreting In the past, splits such as these were their origin. Although ragged stringers assumed to record clastic incursions As an alternative, we suggest that at and fragments of coal are abundant, iden- into the swamp during the time of peat least some of the siltstone splits near the tifiable plant remains are rare. No upright formation. Under the prevailing Missis- Galatia channel resulted from rafting stems or trunks have been observed or sippi Delta analogue, such splits were of peat layers during deposition of the reported. Roots and paleosol features crevasse splays derived from breaches in Dykersburg. As rising waters drowned are absent (Figures 20 and 21). “Riders” natural levees along the main channel. the peat, trapped air and self-generated of coal detach into the clastic layer from But if clastic sediment was carried into gas made the upper layers buoyant. Agi- both above and below. In some cases, a wetland with standing vegetation, we tated by tidal currents, the upper layers coal stringers cross the clastic split would expect upright stumps and other floated free of their substrate, separating 2 6 Circular 605 Illinois State Geological Survey 2 m Figure 20 Photographs showing the Springfield Coal “split” by mas- sive siltstone in the Millennium Mine. The lower view is a close-up of the upper view. Notice the ragged splay- ing of coal layers into the siltstone from both above and below, with one coal stringer crossing diagonally from the lower to the upper coal “bench.” Combined with the absence of roots beneath the upper bench, such geometry implies that the upper part of the peat deposit was rafted. Enlarged view at right. Brown and yellow stains resulted from iron-rich water seeping through the coal. 27 Figure 21 Photographs of siltstone “splits” in the Springfield Coal. (a) Upper “bench” of coal splitting into multiple layers, with ragged splaying of lower coal layers at the Millennium Mine. (b) Contact between the upper coal bench and a massive siltstone split in American Coal’s Millennium Mine, approximately 0.6 mi (1 km) west of the main Galatia channel. Notice the complete absence of root traces in the siltstone. 28 Sandstone Coal Siltstone Siltstone Siltstone Coal Coal Inferred position of underclay (m) (ft) Underclay Underclay 32.9 10 16.4 5 vertical exaggeration 5:1 164 ft 0 0 50 m Figure 22 Profile view of the disturbance in Figure 21a in the Millennium Mine, Saline County, Illinois. along weak bedding planes. Some of the in the area where it rises. Normal rooted Separating the torn ends is “gray-brown, floating layers drifted away, allowing underclay (claystone) occurs below the very hard massive silty mudstone or sediment-laden water to enter beneath coal outside the disturbance. The coal siltstone, similar to roof material” (John other peat rafts and deposit clastic layers. splays apart both above and below, and Nelson, field notes). Although the feature Obviously, no vegetation or roots grew in large lenses of siltstone occur within the was not clearly exposed, the southern flap this setting. Stringers of peat could float seam. At the crest of the disturbance, the of coal appeared to truncate layering of upward, dangle downward, or occasion- roof is water-bearing sandstone. the siltstone beneath. Notice on the map ally cross from one floating peat mat to that the major disturbance is entirely sur- another. This activity could take place A smaller disturbance occurs near the rounded by normal coal. Disturbances of anywhere in the Dykersburg estuary, not slope bottom in the same mine. Com- lesser intensity lay north of the main one, being limited to margins of the channel pletely surrounded by normal coal, the surrounded on three sides by unaffected that existed while the peat was forming. disrupted area is ovoid in map view, coal. These features lie several hundred about 100 × 260 ft (30 × 80 m). In the feet (meters) west of the Galatia channel central part of the disturbance, the coal Major Disturbances in Coal margin.is torn apart and arches upward on one Related to the planar “splits” are more or both sides. As shown by the sketch Also in Saline County, a large area of dramatic disturbances of the Springfield (Figure 23), in one place the torn edges thin, absent, and disturbed coal inter- Coal. In an example from the Millennium overlap one another by about 33 ft (10 m) rupted the workings of the Dering Coal Mine in Saline County, Illinois (Figure as if repeated by a thrust fault, although Company’s No. 2 Mine on the south side 22), disturbed coal occupies an arcuate no fault is present. The upper end of the of the Galatia channel (Figure 25). The belt that is approximately 820 ft (250 m) torn seam thins markedly, suggesting coal company drove entries across the wide and lies more than 0.6 mi (>1 km) that the peat (still pliable) was stretched, disturbed area, and ISGS geologists Rolf west of the Galatia channel (as mapped accounting for the overlap. Roley and Gilbert H. Cady sketched what by the absence of coal). There is no indi- they saw. By chance, an igneous dike cation that the disturbance connects with Similar in many respects is disrupted intrudes into the coal at the eastern edge the main channel. Within the disturbed coal encountered in the northeast part of the disturbance. On both margins, the area, the Springfield Coal rises abruptly, of the Sahara No. 20 Mine, also in Saline coal splits against a blunt, rounded body undulates strongly, and is torn asunder. County. A map and field sketch portray of gray shale with “varve-like laminae” of The siltstone that underlies the coal part of the major disturbance (Figure light gray siltstone. The sketch indicates within the disruption appears identical 24). The entire Springfield Coal seam is that coal and shale interfinger and that to siltstone overlying the coal. No roots torn apart, leaving ragged terminations. shale bedding is deformed in a manner or paleosol features occur below the coal The southern end of the torn coal arches suggesting forcible intrusion. up, partly overlapping the northern end. Illinois State Geological Survey Circular 605 29 Min e m iu nn Mil le Disturbances A B Big Creek Mine Slope 0 .5 1 mi N 0 .5 1 km WEST Mine roof EAST Siltstone Coal Siltstone Coal Approximate scale Mine floor 0 10 20 m 0 32.81 65.62 ft 5 m 16.4 ft Figure 23 Profile view of the disturbance in Figure 21b in the Millennium Mine. The map shows the relationship to the Galatia channel. Location of profile is B on map. 30 Galatia channel Mined area Minor disturbance Major disturbance Mined area 0 .5 1 mi N 0 .5 1 km NORTH Mine roof SOUTH loor Mine f 0 16.6 33 ft 0 5 10 m Figure 24 Map and cross section of the disturbance in the Sahara No. 20 Mine, Saline County, Illinois. 31 el Galatia chann e ous dik Igne > 32 0 .5 1 mi N 0 .5 1 km l cha nne a Gala ti Cross section > Cross section Mined area Thin, absent, or disturbed Mined coal area WEST EAST Coal Gap ~300 m Coal Igneous dike Figure 25 Map and cross section of the disturbance in the Dering Coal Company No. 2 Mine, Saline County, Illinois. Redrafted from field sketches by Rolf Roley and G.H. Cady in the ISGS archives. Another major disturbance was encoun- deposited within the seam and between Abundant continuous cores and under- tered in the northern workings of the the peat and the underclay. When cur- ground mine exposures in the Dykers- Wabash underground mine in Wabash rents stretched part of a torn peat mat, burg Member, including the continuous County, Illinois. Meier and Harper (1981) the ends of the mats could overlap. As the profile in the Galatia Mine, show no bio- described and illustrated the feature, sup- water level continued to rise, eventually turbated strata that could be compared plemented by observations by ISGS geol- the floating peat mats were completely to modern natural levees. Crevasse splays ogists. Where crossed by mine entries, encased in Dykersburg sediment. Dif- cannot develop without natural levees. the disrupted area was about 656.2 ft (200 ferential compaction then deformed the As Coleman (1976) explained, a crevasse m) wide, flanked by normal coal on both sediment, perhaps squeezing some of it splay is basically a small delta having its sides, and lying at least 1,968.5 ft (600 m) laterally. As an example, the major distur- own distributary channels, delta front, south of the Galatia channel, as mapped bance in the Wabash Mine is illustrated to and prodelta deposits. Crevasse splays by the absence of coal. Within the dis- show hypothetical ripping and rafting of are fan-shaped in map view and wedge- turbance, the coal seam rises sharply, peat (Figure 27). shaped in cross section. The coarsest and the lower part is torn out in a highly sediments drop out close to the levee irregular fashion (Figure 26). The rock Smaller disturbances that are completely break; as the splay progrades into the bay that replaces and invades the coal is gray surrounded by “normal” coal (e.g., Mil- or marsh, it develops an upward-coars- siltstone to fine-grained sandstone that is lennium slope and Sahara No. 20) prob- ening profile. Although the Dykersburg largely massive but that shows contorted ably began as blisters of floating peat Shale locally displays upward-coarsening lamination and contains many ragged that eventually burst, allowing sediment sequences, in most cases the grain size is stringers and chunks of coal. No roots or to infiltrate beneath. Some of the larger either uniform throughout the member paleosol features were observed below disruptions, such as the one in the Dering or varies in a random fashion. the disrupted coal. No. 2 Mine, seem to involve tidal chan- nels that connect directly to the main In the past, features such as these were Galatia channel. Origin of the Dykersburg Member generally interpreted as “splits” that Many features of the Dykersburg Member formed when sediment was washed into Absence of Natural Levees point to rapid deposition in a tidal the peat swamp, accompanied by cur- regime: rents that washed away some of the peat We have already shown that no natural • Burial of tree stumps in the growth and perhaps an element of “slumping” to levees flanked the Galatia channel while position account for the observed deformation of the Springfield peat was accumulating. • Superb preservation of delicate plant layering. Specifically, Meier and Harper Likewise, no levees existed during depo- fossils (1981, p. 14) invoked “wedges of fine- sition of the Dykersburg Member, and grained sediment, possibly a crevasse this member and this unit appear to have • Sparse brackish-water invertebrate fauna splay or overbank muds derived from the been deposited in estuarine sedimentary Galatia channel,” subsequently “thrown environments rather than as crevasse- • Scarce burrowing and the absence of into a series of ridges and troughs, pos- splay deposits, as proposed by previous rooting sibly by gravitational slumping on a slope authors. • Scouring of peat tops (rolls) formed by differential compaction.” Such Natural levees of the modern Mississippi • Large-scale splits involving rafted peat models view “splitting” as contempora- Delta are seldom higher than about 6.6 • Prevalent tidal rhythmites neous with peat accumulation. But con- ft (2 m) and are routinely overtopped by • Common slump and load features temporaneous splitting cannot account the floods that sustain them. Levees are • Large-scale clinoform bedding for lifting the peat above its underclay, composed of intermixed clay, silt, and tearing it partly or entirely apart, and The Dykersburg occurs in narrow bands sand exhibiting a variety of sedimentary inserting a wedge of Dykersburg-like on either side of the Galatia channel. structures, especially climbing ripples. sediment between the coal and under- Although the pattern is intricate, the These sediments are intensively rooted clay. Explaining such geometry requires a Dykersburg belt overall widens toward and burrowed, and they contain plenti- new concept. the southwest, resembling a funnel in ful diagenetic iron carbonate (siderite) map view (Hopkins 1968). The pattern We propose that like the small planar and iron oxide nodules (Coleman 1976). is consistent with an estuary, as Archer splits, these dramatic disruptions formed Inferred natural levees in Pennsylvanian and Kvale (1993) proposed. This estuary when rising water rafted large masses of rocks of eastern Kentucky likewise are developed when a rapid rise of sea level peat during the early stages of Dykersburg mostly less than 5 ft (1.5 m) high and 500 drowned the coastline. The Francis Creek deposition. Rafting could involve just the ft (150 m) wide, although a few are larger. Shale overlying the Colchester Coal and upper layers or the entire thickness of the These comprise a poorly sorted, unevenly the Energy Shale overlying the Herrin peat deposit. Agitated by tidal currents, layered mix of claystone, siltstone, fine Coal are close analogues to the Dykers- floating peat mats frequently tore apart, sandstone, and thin lenticular coal. Root- burg, and they share nearly all the fea- admitting sediment-laden water beneath ing is prevalent. Bedding typically dips tures listed above. Estuarine models have the peat. In this manner, thick wedges of gently away from the parent channels been proposed for both the Francis Creek mudstone and siltstone could have been (Baganz et al. 1975; Horne et al. 1978). (Kuecher et al. 1990; Baird 1997) and the Energy Shale (DiMichele et al. 2007). Illinois State Geological Survey Circular 605 33 0 1 in. 0 3 cm Coal Rock parting (ft) (m) –320 0 15 ft 0 5 m Roof –100 –330 –340 ck pa rting Ro –105 Coal N 63º E–350 a Figure 26 Drawings from Meier and Harper (1981) illustrating a major disruption of the Springfield Coal in AMAX Coal’s Wabash Mine in Wabash County, Illinois. The preservation of upright tree stumps down at such a pace. Overall sedimenta- transported up the estuary from offshore and the packages of neap–spring tidal tion rates were limited by the rising base sources by flood tides. Alternatively, a rhythmites indicate that Dykersburg sedi- level, tectonic subsidence, and compac- large increase in fluvial runoff is sug- mentation locally was rapid. Although tion of peat and clastic sediment, which gested. A climate shift from ever-wet we have not systematically measured together typically account for millimeters to a seasonally dry, monsoonal regime and counted neap–spring cycles, they are per year. However, in tidal environments, accompanied the global deglaciation that commonly 0.4 to 2 in. (1 to 5 cm) thick, if accommodation space is available, that brought about sea-level rise. With long equating to deposition rates of about space can be filled rapidly. annual dry spells, less vegetation cloaked 3.3 ft (1 m) in 2 to 10 years. By analyzing upland source areas. Therefore, the sedi- rhythmites, Kuecher et al. (1990) deter- What caused the transition from the ment load and transport in the Galatia mined that parts of the Francis Creek sediment-starved black-water channel river system dramatically increased in Shale were laid down at a rate of about 3.3 during peat formation to a much greater harmony with sea-level rise in the estu- ft (1 m) per year. Of course, such findings load of coarser sediment is unknown. ary. This process is consistent with the do not show that the entire unit was laid Although no evidence is available, some relationship observed between climate Dykersburg sediment may have been 3 4 Circular 605 Illinois State Geological Survey ? ? ? Mineheading ? Underclay Figure 27 (Top) Image of the major disturbance in the Wabash Mine. From Meier and Harper (1981). (Bottom) The same drawing with interpretation added, depicting the peat deposit torn asunder, with the upper part floated away from the lower. The seam height at the left side of the diagram is approximately 9 ft (2.7 m). and sediment transport in modern tropi- Mine is readily identified by very high The gray, nonmarine Energy Shale cal river systems (Cecil and Dulong 2003; readings on gamma-ray logs (Figure 5) Member that overlies the Herrin Coal Cecil et al. 2003a) and with the potential and low readings on density and neutron near the contemporaneous Walshville for a rapid, pulse-like rise of sea level in logs. channel is a close analogue to the Dyk- association with deglaciation (Archer et ersburg Shale. The contact of the Energy al. 2016). The contact between the Turner Mine Shale to the overlying black, phosphatic and Dykersburg Shale varies from rapidly Anna Shale has been observed and gradational to erosive. Unfortunately, Turner Mine Shale Member mapped in large areas of several under-few mines exposing this contact have ground mines. This contact is sharply The Turner Mine Shale is the first marine been active within the last 40 years. In erosive, cutting off Energy Shale bedding bed to follow the Springfield Coal, the the Eagle No. 2 underground mine in at angles as steep as 20°. The Energy Shale Dykersburg Shale, or both. It is black, Gallatin County, Illinois, Dykersburg can be truncated from more than 15 ft fissile, and phosphatic and lies directly Shale occurred in lenses less than 2 ft (60 (4.5 m) thick to zero in a lateral distance above the Springfield Coal throughout cm) thick, grading into overlying Turner of 100 ft (30 m). Such erosion explains the Illinois Basin wherever the Dykers- Mine Shale. Evidently, this mine lay at the the highly irregular, lobate, and podlike burg Member is absent. The Turner Mine eastern depositional limit of the Dykers- distribution of gray shale as mapped in also overlaps the Dykersburg (Figure 4) burg. At the Willow Lake Mine in Saline the mines (Bauer and DeMaris 1982; but typically pinches out where the Dyk- County, closer to the Galatia channel, Nelson et al. 1987). Similar erosion evi- ersburg reaches a thickness of 33 ft (10 m) lenses of Dykersburg were more numer- dently affected the Dykersburg prior to or more. The Turner Mine averages about ous and ranged up to 3.3 ft (1 m) thick. deposition of the Turner Mine Shale. The 3.3 ft (1 m) thick, ranging from less than Here, the contact was clearly erosive, with inferred origin of the Turner Mine Shale 1 ft to 8 ft (0.3 to 2.4 m) thick. The Turner the Turner Mine lying against truncated is essentially the same as that for the bedding of the Dykersburg. Excello Shale. Illinois State Geological Survey Circular 605 35 St. David Limestone Member interval between the St. David Limestone approximately the same region as the The St. David is marine limestone that and the Briar Hill Coal (Figure 4). The fol- southeastern area of thick Springfield overlies the Turner Mine Shale (Figure 4). lowing information is based on a cursory Coal. It extends above the Galatia chan- Savage (1927) named the unit, whereas inspection of selected core records and nel except where the Dykersburg Member Wanless (1956) designated (but did not observations in mines. approaches its greatest thickness. Gen- describe) a type section in Fulton County, erally, the Briar Hill is a single bench of Generally, the Canton is an upward- western Illinois. The name “Alum Cave bright-banded coal between 9.8 and 19.7 coarsening succession of shale, siltstone, Limestone” has been used for the same in. (25 and 50 cm) thick. The maximum and fine-grained sandstone. Shale in the unit in Indiana. Wanless (1939) was the known thickness is about 50 in. (130 cm) lower part contains numerous bands first to use Alum Cave in its present sense. in Sullivan County, Indiana. Where the and nodules of siderite. Brachiopods The name St. David therefore has priority Briar Hill is thinner than 10 in. (25 cm), and other marine fossils are common and is used in this report. the coal commonly becomes shaly. The near the base. Sandstone in the upper Briar Hill rests on a weakly developed The St. David is medium to dark gray, Canton tends to be shaly and thinly lay- paleosol, commonly little more than a argillaceous, lime mudstone to wacke- ered. A few well records indicate a sharp thin, root-penetrated interval of lami- stone containing an abundant normal- contact between upper sandstone and nated silty mudstone or siltstone. Above marine fauna of brachiopods, bivalves, lower shale, but deep channel incision is the coal is a shaly succession that typi- gastropods, cephalopods, ostracods, cri- unknown. At the top of the Canton is the cally coarsens upward. A thin layer of noids, fusulinids, and bryozoans (Savage weakly developed underclay of the Briar impure marine limestone or fossiliferous 1921; Wanless 1957; Shaver et al. 1986). Hill Coal. The thickness of the member shale may occur at the base. No black is normally 10 to 50 ft (3 to 15 m), but the phosphatic shale, comparable to the The member is practically coextensive Canton reaches 82 ft (25 m) thick in Web- Excello or Turner Mine Shale, accompa- with the Springfield Coal. In the Fairfield ster County, Kentucky. nies the Briar Hill Coal. Basin and parts of western Kentucky, the limestone is less than 1 ft (30 cm) Two problems arise in defining the thick and consists of dark gray, argil- Canton Shale. One problem, which does Summary laceous, fossiliferous lime mudstone not concern this study, arises where to wackestone. On the Eastern Shelf in the Briar Hill Coal is absent and the 1. The Houchin Creek Coal formed as Indiana, the limestone is as thick as 10 Canton cannot be distinguished from an in situ peat deposit on a vast, level, ft (3 m) but more commonly 1 to 4 ft the unnamed clastic rocks overlying the stable coastal plain. (0.3 to 1.2 m), in two layers separated by Briar Hill position. The other difficulty is 2. The Excello Shale records rapid marine transgression to the point thin shale (Wier 1961). In northwestern separating the Canton from thick Dykers- Illinois, the unit is normally a few inches burg Shale where the Turner Mine and St. where bottom water became anoxic (centimeters) to about 2 ft (60 cm) thick David Members are missing. Core records because of the absence of circulation but locally exceeds 6.6 ft (2 m; Wanless indicate that the Canton thins to less than and the abundance of plant-derived 1957). Thicker St. David, lighter colored 9.8 ft (<3 m) where the Dykersburg is organic matter. and less argillaceous than that found thicker than about 49.2 ft (15 m). 3. The Hanover Limestone reflects in the basin, also occurs on areas of the restoration of normal marine circula-In depositional terms, the Canton Shale is Western Shelf where the Springfield Coal tion in deep water offshore, probably more or less a repetition of the Delafield is thick enough to mine. Along with the under a seasonally dry climate.Member. The unit reflects the shoreline Turner Mine Shale, the St. David pinches 4. The Delafield Member records pro-prograding into a shoaling basin during out where the Dykersburg Shale is thick gradation of the shoreline into brack-highstand to early regression. (~32.8 ft [10 m] or more). ish water under a falling sea level, essentially filling the basin with clas- The limestone closely resembles the Briar Hill Coal tic sediment. older Hanover Limestone and probably The youngest unit considered in this 5. The Galatia Member fills an incised was deposited under similar conditions. report, the Briar Hill Coal (Figure 4) is valley that was cut and filled during Like the Hanover, the St. David appears thin but widely persistent in southeast- regression to early lowstand. The to have developed better in the shallow ern Illinois, southwestern Indiana, and river meandered actively and carried waters at the margins of the Illinois Basin western Kentucky. Glenn (1912) named a heavy load of sand, rapidly backfill- than in the deeper waters of the basin the coal in Union County, Kentucky, ing its meander belt. interior. whereas Butts (1925) extended the Briar 6. Springfield peat formation com- Hill into southeastern Illinois. The same menced during lowstand (maximum Canton Shale coal in Indiana has been called the Buck- glaciation) under an ever-wet climate Savage (1921) named the Canton Shale town Coal Member (Shaver et al. 1970). that produced a perennially high for the city of Canton in Fulton County, Because Briar Hill has priority, usage of water table. Vegetation stabilized western Illinois. Little has been published Bucktown should be discontinued. meanders of the Galatia channel, about this unit. As depicted by Willman et which transitioned to a black-water The Briar Hill is confined to the south- al. (1975), the Canton Shale occupies the stream that carried only fine-grained eastern part of the Illinois Basin in sediment. There were no natural 36 Circular 605 Illinois State Geological Survey levees, but belts of laminated shaly (1982, figure 2) showed on a small-scale out in large sheets. Core drilling demon- coal flank the Galatia channel. map “known contemporaneous chan- strated that shaly coal borders both sides 7. The Dykersburg Member records the nels” in Knox and Sullivan Counties and of the channel in Sullivan County. onset of transgression, which con- suggested that they join the Galatia chan- Although details are sparse, previous verted the Galatia channel to an estu- nel. Eggert and Adams (1985) discussed these features in more detail. Harper authors (Kottlowski 1954; Wier 1954; ary and drowned the peat swamp. Vigorous tidal currents dislodged (1988) and Harper and Eggert (1995) pre- Harper 1988; Harper and Eggert 1995) sented further maps and information. reported that numerous abandoned floating mats of peat, creating rolls, underground mines encountered areas of splits, and localized major disruption Combining information from these “dirty” or “shaly” coal, along with lenses of the seam. As the climate became sources with newly acquired coal com- of shale or sandstone, near the margins of seasonally dry, the fluvial runoff and pany data, we present a more complete the Sullivan channel. sediment load increased. Gray Dyk- picture of the Sullivan channel (Plate 1). ersburg clastics rapidly entombed The Sullivan channel is a nearly straight Several sizeable tracts of thick, low-sulfur the peat. to strongly sinuous belt about 0.6 to 1.6 (0.4% to 1%) coal flank the Sullivan chan- 8. Deposition of the marine Turner mi (1 to 2.5 km) wide where clastic rocks nel. Most of the thickest coal, ranging Mine black shale, St. David Lime- occupy the position of the Springfield from 7 to 11 ft (2 to 3 m) thick, occurs in stone, and younger units completed Coal. Drilling indicates a “precursor” steep-sided structural depressions. As the story. valley filled largely with sandstone and usual, low-sulfur coal is overlain by thick The Galatia channel provides insights extending as deep as 215 ft (65 m) below gray shale, siltstone, and sandstone of the into events that are not recorded in the position of the Springfield. This chan- Dykersburg Member. The largest of these most Carboniferous cyclothems. This nel truncates the Houchin Creek and Sur- areas is the Glendora district in northern example indicates, in conformance with vant Coals, cutting within 15 ft (4.5 m) of Sullivan County (Plate 1), where the coal some other studies (e.g., Cecil et al. 1985, the Colchester Coal. Channel filling gen- lies in a structural basin about 30 ft (9 m) 2003b, 2014; Eros et al. 2012; Horton et erally fines upward, grading to siltstone deep and is topped by up to 30 ft (9 m) of al. 2012; DiMichele 2014), that glacially or claystone at the level of the Springfield. Dykersburg shale and sandstone (Kott- driven sea-level fluctuations were linked These strata are basically identical to the lowski 1954; Wier 1954; Harper 1988). to climate changes in the tropics. It also Galatia Member as it occurs in the main Nearly surrounded by thin, shaly coal, the refines our understanding of when cer- Galatia channel. Glendora district appears to lie between tain events (such as the development of branches of the Sullivan channel. The peat) took place within the eustatic and Belts of interlaminated coal and carbo- active Carlisle and Oaktown Mines both climatic cycle. These themes are devel- naceous shale, like those found along contain steep-sided troughs where the oped further in a later section of this the Galatia channel, border the Sullivan coal thickens markedly and has a gray, report. For a more complete understand- channel. For example, at the eastern siliciclastic roof. However, in most areas ing of the Galatia channel, it is necessary margin of the channel in the Oaktown of these mines, the Turner Mine Shale lies to investigate other paleochannels related Mine in Knox County, the Springfield directly on the coal. to the Springfield Coal. Coal is thicker than 15 ft (4.5 m) but con- tains approximately 70% carbonaceous Thus, the Sullivan channel shares all the shale laminae (Figure 28). Fossil plant attributes of the Galatia channel. The Sul- OTHER CHANNELS stems (Sigillaria) and foliage (Pecopteris, livan is either a direct northward continu- RELATED TO THE GALATIA Neuropteris) are abundant in the shale ation of the Galatia or a major tributary. CHANNEL layers. Shale content gradually dimin-ishes eastward, yielding coal with no Effingham Channel Several paleochannels have been clastic layers about 5.6 ft (1.7 m) thick at mapped that are similar to the Galatia 0.6 mi (1 km) from the channel. The floor Across most of the basin, the upward- channel in age and mode of formation. also changes from a massive siltstone coarsening Delafield Member underlies Previous authors have named some of having few roots and slickensides close the Springfield Coal. However, Potter’s these channels; others are named herein. to the channel to a well-developed clay- (1962, 1963) maps depict several large stone paleosol away from the channel. meandering and dendritic sand bodies, Shaly coal also occurs along the western evidently paleochannels, that replace the Sullivan Channel margin of the Sullivan channel in the Delafield Member below the Springfield A large paleochannel that interrupts the Carlisle Mine, about 9 mi (15 km) north of Coal. The largest of these paleochannels Springfield Coal in Sullivan and Knox Oaktown in Sullivan County (Figure 29). trends southeast from central Illinois to Counties, Indiana (Plate 1), is here named As in the Oaktown Mine, shale laminae southwestern Indiana (Figures 1 and 8, the Sullivan channel. Several previous contain abundant fossil plants, includ- Plate 1). This feature is hereby named the authors have mapped portions of the Sul- ing Calamites stems and broken leaves Effingham channel after the city of Effing- livan channel and described some of its of Neuropteris and Macroneuropteris. In ham, Illinois, which lies near its course. effects. Wier and Powell (1967) mapped this same area, the floor of the Springfield Comparing Potter’s map (Figure 30) with two elongate areas where the Springfield consists of laminated shale that contains those of Hopkins (1968), Treworgy and Coal is absent in Knox County. Eggert abundant fossil plants and can be lifted Bargh (1984), and Treworgy et al. (1999), we observed the following: Illinois State Geological Survey Circular 605 37 0 0 30 cm 1.0ft Figure 28 Photograph of interlaminated carbonaceous shale and bright to dull coal close to the margin of the Sullivan channel in the Oaktown Mine in Knox County, Indiana. 38 0 0 50 cm 2 ft Figure 29 Photograph of interlaminated carbonaceous shale and bright to dull coal close to the margin of the Sullivan chan- nel in the Carlisle Mine in Sullivan County, Indiana. • The Effingham channel widens has a wide, nearly flat bottom and steep The lower sequence is about 15 ft (4.5 toward the southeast, and several sides. The base is cut close to the Houchin m) thick and is largely sandstone, fining tributaries are “barbed” toward the Creek Coal. Many wireline logs indicate upward from an erosive lower contact. northwest. Thus, it evidently flowed two sedimentary sequences filling the Cross-bedding in the lower part gives southeast. Effingham channel. The lower sequence way to planar lamination having well- • The Effingham channel crosses the is largely sandstone, fining upward and developed neap–spring tidal couplets southwest-trending Galatia channel at ranging from about 20 to 50 ft (6 to 15 m) near the top. The upper sequence is 23 ft a right angle. thick. A few logs show a thin, highly resis- (7 m) thick and is largely sandstone, grad- • The Effingham channel does not tive bed at the top of the lower sequence. ing to blocky, rooted claystone at the top interrupt the Springfield Coal, and A density–neutron log (Figure 31) from beneath the Springfield Coal. the coal does not appreciably thicken the Berry Petroleum No. 11-14 Pitcher well in Jasper County confirms that the The Springfield Coal locally thickens along its margins. resistive bed is coal. The upper sequence above the Effingham channel, as shown • The Effingham channel exhibits is 20 to 30 ft (6 to 9 m) thick and is mostly on the map by Treworgy et al. (2000). This meander-belt geometry (in map view) shale and siltstone. In some cases, the is most obvious along the west branch of similar to the Galatia channel. sequence fines upward from basal sand- the channel in southern Shelby County • No Dykersburg Shale is associated stone, but other logs show an upward- (Plate 5), which suggests that the channel with the Effingham channel. coarsening profile. The best record is con- was incompletely filled, leaving a trough Cross sections (Plates 4 and 5) show that tinuous core from the ISGS No. 1 Elysium to be filled with thicker peat. There is no the Effingham channel, like the Galatia, borehole in Richland County (Figure 32). shaly coal or other evidence for an active Illinois State Geological Survey Circular 605 39 l nne ia c ha ala t G 0 10 mi 0 10 km N Figure 30 Map from Potter (1962) showing the Effingham channel as described in this report. 40 Gamma Ray Density/Neutron Danville 245.37 1,200 130.41 Herrin 224.45 1,250 174.74 Springfield Coal 203.71 1,300 105.25 Effingham channel Houchin Creek 185.73 1,350 95.52 Figure 31 Gamma-ray–neutron log from the Berry Petroleum No. 11-14 Pitcher well in Jasper County, Illinois, indi- cating coal in the upper part of the Effingham channel fill. stream occupying the channel during the its developed in the abandoned waterway Leslie Cemetery Channel time of peat formation. before a second stage of fluvial activity Eggert (1978, 1982, 1984, 1994), Eggert completed backfilling of the channel. Cross-cutting relationships indicate that and Adams (1985), and Willard et al. the Effingham channel is older than the This scenario introduces complications (1995) described a belt of “split” Spring- Galatia channel (Figure 33). After estab- into how the Effingham channel fits into field Coal in southwestern Indiana and lishing its meander belt, the Effingham eustatic cycles. A possible solution is called this feature the Leslie Cemetery system was abandoned and backfilled explored in the Discussion section. channel (Figure 34). Our observations in with sediment. Locally, small peat depos- active surface mines and those of other Illinois State Geological Survey Circular 605 41 Depth ISGS geologists provided further informa- (ft) tion. A revised map of the channel (Figure 1,120 35) is based on newly available data from active mines and boreholes. In addition, a cross section (Plate 6) has been con- Canton Shale structed using borehole data. The Leslie Cemetery channel is slightly sinuous in map view and varies from St. David Limestone about 0.9 to 3.7 mi (1.5 to 6 km) wide. Turner Mine Shale It trends northwest from the outcrop in Warrick County into eastern Gibson Springfield Coal County, where it intersects the Galatia channel. In sectional view (Plate 6), the Leslie is lens-shaped, reaching 65 ft (20 1,140 m) thick along its central axis. Unlike the Galatia channel, the Leslie Cemetery splits the Springfield Coal, with the upper “bench” of coal overriding the clastic rocks that fill the channel (Figure 36 and (m) Plate 6). The Turner Mine Shale and St. 0 David Limestone directly overlie the upper coal bench. The lower bench of the Springfield Coal is generally 2 to 4 ft (0.6 to 1.2 m) thick and Galatia Member lacks clastic layers. Ash and sulfur content are moderate to low. In terms of petrog- 1,160 raphy and palynology, the lower bench is similar to Springfield Coal elsewhere near Neap–spring rhythmites the Galatia channel (Willard et al. 1995). The lower bench dips into a trough below 5 the channel (Figure 36) and is nearly con- Effingham tinuous, except in a few places where the channel channel truncates the coal. fill Filling the Leslie channel is a succession of gray mudstone, siltstone, and fine- grained sandstone that Eggert (1982) Delafield Member named the Folsomville Member. Near the margins of the channel, the Folsomville 1,180 consists largely of nonfissile, slickensided Excello Shale claystone and thinly laminated, organic- Houchin Creek Coal rich carbonaceous shale. As the Fol- somville thickens, it changes to layered gray mudstone and siltstone containing laminae and lenses of sandstone along with siderite nodules and concretions. Toward the axis of the Leslie Cemetery channel, sandstone becomes more preva- lent and commonly shows cut-and-fill features. Cross-bedding is unidirectional and indicates a paleocurrent toward the 1,200 northwest; no indications of tidal sedi- mentation have been recognized (Willard Figure 32 Graphic log of core from Richland County, Illinois, showing et al. 1995). Fossil plants are locally abun- filling of the Effingham channel. The core shows two upward-fining dant in the finer grained rocks, especially sequences, the lower having tidal rhythmites in the upper part. The prone stems and logs of lycopsids and borehole is ISGS No. 1 Elysium (Hazel Farm) in sec. 27, T 4 N, R 9 E pteridosperm foliage, along with roots of (county no. 25922). lycopsids, pteridosperms, and calamites. A rooted “seat earth” commonly occurs 4 2 Circular 605 Illinois State Geological Survey m ft 0 0 Springfield Coal 10 coal 40 Galatia Effingham 20 80 Excello Shale Figure 33 Interpretive cross section of the Effingham channel in Richland County, Illinois, showing two stages of infilling, with local coal at the top of the lower stage. a b R10W R9W R8W Contemporaneous coal absent Galatia Extent of channel Contemporaneous coal split Springfield SpringfieldCoal absent Coal Member T Erosional coal absent 2 S IL IN STUDY AREA KY T 3 S Winslow channel Winslow-Hendersonchannel Galatia channel STUDY AREA T 0 5 mi Evansville Leslie 4 N Cemetery S 0 5 km RIVRE . R channel OHIO THICKNESS (ft) Henderson 0 30 mi channel 0–5 0–10 >>10 N 0 50 km Figure 34 Maps of the Leslie Cemetery channel. (a) Regional map showing the relationship to other channels. (b) Map of the northern part of the Leslie Cemetery channel, with the thickness of the Folsomville Member. From Eggert (1984), The Leslie Cemetery and Francisco distributary fluvial channels in the Petersburg Formation (Pennsylvanian) of Gibson County, Indiana, U.S.A., in R.A. Rahmani and R.M. Flores, eds., Sedimentology of coal and coal-bearing sequences: International Association of Sedimentologists, Special Publication 7 p. 311, 313. Copyright © 1984 The International Association of Sedimentologists. 43 WABASH RIVER IL IN 10W 9W 8W el han n atia c Gal 2S Leslie Cemetery channel 3S nel cha n rso n end e Pike 7W -H low Warrick insW ! ! ! Gibson ! ! Warrick ! ! ! ! 4S ! ! 1:200,000 Les 0 2 4 mi ! lie ! C ! emetery 0 2.5 5 km channel 5S Coal mine (underground) Coal mine (surface) Figure 35 Map of the Leslie Cemetery channel prepared for this study, using information from boreholes and mines. Lines of section for Figure 36 and Plate 6 are shown. below the upper coal bench (Willard et In places, the upper bench grades to 1995; Phillips and DiMichele 1998). Con- al. 1995). Eggert (1982) reported fossil carbonaceous shale or to thinly inter- odonts were recovered from coal balls tree stumps in growth position, and we laminated coal and shale (Figure 36). In near the top of the upper bench in the observed several at the Cypress Creek some places, the upper coal is continuous Lynnville Mine. Mine near the margin of the channel. above the channel, but in other sites, it These stumps were rooted in, or a short pinches out. The flora is dominated by Like the Galatia channel, the Leslie distance above, the lower coal bench. Spi- lycopsids accompanied by calamites, pte- Cemetery channel overlies an older “pre- rorbid worm tubes, as reported by Willard ridosperms, and tree ferns, but ground- cursor,” which Eggert (1984) named the et al. (1995), are the only invertebrates. cover plants are uncommon (Willard et Francisco channel. The well-log cross al. 1995). Calcareous coal balls occurred section (Plate 6) illustrates this relation- The upper bench of coal ranges from a in the upper bench at both the Lemmon ship. Underlying the Springfield Coal, the few inches (centimeters) to 2.3 ft (0.7 Brothers and Lynnville Mines, on oppo- Francisco channel truncates the Delafield m) thick and carries a much higher ash site margins of the channel (Willard et al. Member and is filled with an upward- and sulfur content than the lower bench. 44 Circular 605 Illinois State Geological Survey Vanderburgh Warrick Pigeon Creek Section Gibson Pike Outcrop of Springfield Coal E E l ld C oa gfie f Sp rin o tcro p Ou 45 SOUTH NORTH St. David Limestone Turner Mine Shale upper bench Generalized cross section Springfield Coal of highwall, Lynnville Mine lower bench July 27, 1983 Springfield Coal width of profile about 2/3 mile 0 100 200 300 400 500 ft SOUTH NORTH m ft 0 50 100 150 m surface 50 Canton Shale 15 limestone calcareous shale 40 St. David Limestone Turner Mine Shale 10 upper bench 30 Springfield Coal 20 split material-silty 5 shale with plant fossils 10 no. 4 incline 0 0 lower bench Eby Pit no. 3 Springfield Coal June 26, 1982 incline Figure 36 Generalized sketches illustrating opposite margins of the Leslie Cemetery channel, as exposed in surface mines in the eastern half of 9S, 4W, Warrick County, Indiana. The upper image is from Peabody’s Lynnville Mine in July 1983, representing the northern half of the channel. The lower image is from Peabody’s Eby Pit in June 1982, representing the southern half of the channel. a Water Delafield Member Francisco channel Excello Shale b c d Water Leslie Cemetery channel Francisco channel Figure 37 Interpretive diagram showing sequential development of the Leslie Cemetery channel. (a) The Francisco channel is eroded and filled with sediment, largely sand. (b) Springfield peat accumulates in swale left by the abandoned channel. (c) Flowing water reoccupies the channel during the later stages of peat accumulation. Peat encroaches from the margins as the channel migrates laterally. (d) A marine incursion drowns the region and deposits black shale and limestone. Channel filling inverts the topography because of differential compaction. fining succession of sandstone, siltstone, The observations outlined above suggest course, however, remained as a trough and shale. Borehole data (Eggert 1982) the Leslie Cemetery channel developed through the peat swamp; the lower coal indicate that underclay is at least locally by the following sequence of events bench formed in this trough (Figure 37b). absent below the lower coal bench, (Figure 37). The Francisco channel was a Partway through peat formation, flowing which rests directly on sandstone. The northwest-flowing tributary of the Galatia water reoccupied the trough, depositing Francisco channel is less deeply incised precursor channel. Prior to the onset of clastic sediment in the Leslie Cemetery than the Galatia channel; the Francisco peat formation, the Francisco channel channel. The active channel migrated lat- does not cut out the Houchin Creek Coal. was filled with clastic sediments and erally, and plants grew in standing water Evidently, the Francisco was a tributary to abandoned (Figure 37a). The channel along its margins. Peat and sediments the Galatia channel. 46 Circular 605 Illinois State Geological Survey compacted, making space for more sedi- R10W R10W ment. During later stages of Springfield peat development, the channel again was 28 27 26 25 30 29 28 largely abandoned, and peat accumu- lated above channel sediments (Figure 37c). Marine transgression finally termi- Terre nated peat formation. Coal balls devel- T Haute oped, and the Turner Mine and St. David 12 33 34 35 36 31 32 33 N Members were deposited above the Leslie Cemetery channel (Figure 37d). B 4 3 61 r 5 4 Other Channels 2 Rive Potter (1962, 1963) mapped other chan- nel-form sandstone bodies below the B′ Springfield Coal that do not correspond 9 10 11 12 7 8 9 to interruptions in the coal. These include Wabash a series of branching, strongly meander- ing channels in southern Illinois, largely T A Franklin, Hamilton, Saline, and Gallatin 11 16 15 14 13 18 17 16 N Counties (Figure 8). Widths are in the range of 0.6 to 1.9 mi (1 to 3 km). Portions appear dendritic with tributaries, but 22 the overall drainage direction is unclear. 21 23 24 19 20 21 These likely represent more than one channel; one segment appears to cross A′ the Galatia channel at nearly a right Channel-fill sandstone, coal mostly absent angle. More channels mapped by Potter are in Bond, Clinton, Washington, and Thin shale split in coal 0 1 2 mi Perry Counties of southwestern Illinois. Coal V greater than 3.7 feet thick N0 1 2 km These sinuous features branch and rejoin but do not exhibit (as mapped) an inte- Borehole grated drainage. We have not investigated Mine shaft these channels and will offer no further comments. m ft Friedman (1956, 1960) mapped an A 40 area near Terre Haute, Indiana, where A′ 10 the Springfield Coal is split and partly 30 replaced by sandstone and shale. He called this feature the Terre Haute chan- 205 nel. Friedman’s map (Figure 38) shows 10 a southwest-trending channel about Coal V 1,300 ft (400 m) wide, with several short 0 0 branches joining from the southeast. In Terre Haute one area, the coal divides into a continu- B channel sandstone Coal Vb B′ ous lower bench and an upper bench that thins and pinches out toward the channel axis. In another area, shale layers occur in the coal along a linear trend, although the Coal Vb coal is not cut out. Sandstone is largely confined to the main channel. Maximum clastic thickness is about 40 ft (12 m). Harper (1985, p. 19–20) discussed the Coal V Terre Haute channel in relation to the Dresser underground coal mine but did Sandstone Coal Shale Limestone not shed further light on the nature of the disturbance. Friedman (1956, 1960) Figure 38 Map and cross section of the Terre Haute channel. From Friedman inferred a dendritic fluvial system that (1960). Courtesy of the Indiana Geological and Water Survey. Lines of cross was active during later stages of peat for- section are shown on the map. mation. The Terre Haute channel may be Illinois State Geological Survey Circular 605 47 ILLINOIS INDIANA m) t (6 20 f < ha le k S Cr ee is ran c F IL IN ann el ch Thick low-sulfur Danville Coal Oraville channel MO KY TN 0 20 40 60 mi AR N0 40 80 km Figure 39 Map of the Illinois Basin showing channels and gray-shale wedges affecting the Murphysboro, Colchester, Herrin, Baker, and Danville Coals. 48 Walshville Winslow - Henderson similar to the Leslie Cemetery channel, include a remarkable fauna of soft-bodied is moderate to low (0.5% to 2.5%) where but not enough data are at hand to offer a organisms, some known nowhere else the Energy Shale is thicker than about theory of its origin. (Shabica and Hay 1997), along with a rich 20 ft (6 m; Johnson 1972; Allgaier and and diverse flora of land plants (Wittry Hopkins 1975; Treworgy and Bargh 1984; SIMILAR CHANNELS 2006). These fossils have been divided Nelson et al. 1987).into a “Braidwood assemblage” repre- AFFECTING OTHER COAL senting fresh to slightly brackish, tidally The Energy Shale consists of gray mud- stone, siltstone, and sandstone as thick SEAMS influenced water and an “Essex assem- blage” of more saline but not fully marine as 120 ft (37 m). It is thickest and coars- Several well-documented paleochannels conditions (Baird 1997). The Braidwood est near the channel, becoming thin and in the Illinois Basin existed contempo- assemblage and thickest Francis Creek lenticular at its outer limits. The sparse raneously with peat deposits older and Shale are localized near the northeastern fauna comprises brackish-water forms younger than the Springfield (Figure margin of the basin. The Dykersburg lacks such as Lingula, Dunbarella, Myalina, 39). The Galatia channel provides an apt a significant invertebrate fauna, and a the brachiopod Leaia tricarinata, and model for comparison. marine to brackish transition has yet to rare cephalopods and eurypterids. be defined. Fossil land plants are abundant and well preserved, including stands of upright Colchester Coal and Francis All these features point to extremely rapid stumps (mainly lycopsids) rooted at the Creek Shale sedimentation, at least locally. By count- top of the coal (DiMichele and DeMaris The Colchester Coal may be the most ing tidal cycles and measuring their thick- 1987; DiMichele et al. 2007). Locally, the extensive coal bed in North America, if ness, Kuecher et al. (1990) determined Energy Shale contains siderite concre- not the world (Wanless 1975; Greb et al. rates as rapid as 3.3 ft (1 m) per year. tions similar to those of Mazon Creek, 2003). It correlates with the Lower Kit- containing fossils of plants and soft-bod-No “split” Colchester Coal or channels tanning coal bed of the northern Appa- ied invertebrates (Gastaldo 1977; Baird contemporaneous with the coal have lachians and the Croweburg Coal of the et al. 1985b). Shared with the Dykersburg been identified. However, patterns of Western Interior. Cecil et al. (2003b) char- are features including tidal rhythmites Francis Creek Shale distribution and acterized time-equivalent rocks through- (Archer and Kvale 1993; DiMichele et enclosed biota suggest that river mouths out the continental United States. al. 2007), a variety of rolls (Edwards et lay a short distance northeast of the al. 1979; Krausse et al. 1979; Bauer and In most of the Illinois Basin, the Col- present Colchester outcrop (Baird et al. DeMaris 1982; Nelson 1983), and a major chester is too thin to mine (≤1.6 ft [≤0.5 1985a). coal disruption that suggests large-scale m]) and is directly overlain by the black, As with the Dykersburg Shale, early rafting of peat (Nelson 1983, p. 21–23). phosphatic Mecca Quarry Shale, with the models placed the Francis Creek in a Away from the Walshville channel, the marine Oak Grove Limestone above that deltaic setting (Wright 1965; Shabica Energy Shale is eroded into pods beneath (Figure 40). In northern Illinois, the coal 1970). Later authors recognized an estua- the black, fissile, marine Anna Shale. The thickens to as much as 4.6 ft (1.4 m) and is rine component and favored deposition Anna–Energy contact is clearly erosional, overlain by the gray Francis Creek Shale, during transgression of the peat-forming having locally more than 15 ft (4.5 m) of which ranges up to 34 m (112 ft) thick lowland (Baird et al. 1985a, 1985b). relief with bedding of the Energy Shale (Figure 41). Low-sulfur Colchester Coal Archer and Kvale (1993) and Archer et al. truncated at a 20° angle. Finally, the Anna is known from only two mines among the (1995) further emphasized the tidal, estu- and overlying marine Brereton Limestone hundreds that formerly worked this seam. arine aspect. We regard the Francis Creek onlap and pinch out against the tidally These mines had thick Francis Creek; as a series of tidally dominated deltas that deposited, gray siltstone and sandstones however, many other mines having thick accumulated in a broad, brackish embay- that fill the core of the Walshville channel Francis Creek had high-sulfur coal (Glus- ment. (Bauer and DeMaris 1982; DeMaris et al. koter and Hopkins 1970). 1983; DeMaris 2000). The Turner Mine Shale and St. David Limestone pinch out The Francis Creek and Dykersburg Shales Herrin Coal, Energy Shale, in similar fashion where the Dykersburg are closely similar in some respects and and Walshville Channel Member is thick. different in others. Both units encap- sulate upright tree stumps and display The gray, nonmarine Energy Shale and Although no precursor Walshville chan- beautifully developed tidal rhythmites Walshville channel (Figures 42 and 43) nel has been mapped, core drilling in (Kuecher et al. 1990; Baird 1997). The are close analogues of the Dykersburg several areas confirms a deeply incised, Francis Creek shows a more consistent Shale and Galatia channel. Belts of thick sandstone-dominated valley fill below upward-coarsening profile than the Dyk- Herrin Coal (up to 13 ft [4.3 m]) flank the the belt of thick Herrin Coal. As with ersburg. The upper part includes rooted channel, and shaly or “split” coal flanks the Galatia, the precursor Walshville zones, impure coal, channel-form sand- channel margins. Away from the channel, channel is considerably wider than the stone bodies, and features interpreted as the Herrin has a black shale–limestone contemporaneous portion (as defined by crevasse splays and natural levees (Baird roof and uniformly high sulfur content. the absence of Herrin Coal). Moreover, 1997). Most notably, the Francis Creek Near the channel, wedges of the gray the Walshville channel, like the Galatia, bears the famous Mazon Creek fossils, Energy Shale intervene between coal and exhibits looping meanders that did not preserved in siderite concretions. These black shale. The sulfur content of the coal migrate laterally. Illinois State Geological Survey Circular 605 49 (m) (ft) 0 0 West Franklin Limestone Farmington Shale Danville Coal 30 100 Brereton Limestone Anna Shale (black) Energy Shale (gray) Herrin Coal Briar Hill Coal St. David Limestone Turner Mine Shale (black) Dykersburg Shale (gray) Springfield Coal Delafield Member (new) Hanover Limestone Excello Shale (black) Houchin Creek Coal Bevier Coal Survant Coal Wheeler Coal Mecca Quarry Shale (black) Francis Creek Shale (gray) Colchester Coal Dekoven Coal Seelyville Coal Davis Coal Murphysboro Coal Figure 40 Stratigraphic column showing the units mentioned in the section on channels affecting coal seams other than the Springfield. 50 Tradewater Formation Carbondale Formation Shelburn Patoka Formation Fm LA SALLE WILL HENRY BUREAU ROCK ISLAND GRUNDY STARK PUTNAM KANKAKEE KNOX MARSHALL LIVINGSTON WARREN PEORIA WOODFORD MC LEAN FULTON HANCOCK MCDONOUGH FORD TAZEWELL MASON CHAMPAIGN LOGAN SCHUYLER DE WITT ADAMS MENARD PIATT CASS MACONBROWN MORGAN SANGAMON DOUGLAS MOULTRIE PIKE SCOTT CHRISTIAN SHELBY COLES Francis Creek Shale thickness (ft) 0 40 mi <20 Francis Creek Shale not N 0 60 km present or not mapped 20 to 40 Colchester Coal eroded; no coal 40 to 60 60 to 80 >80 Figure 41 Isopach map of the Francis Creek Shale. Authors through the 1980s attributed model calls for a mud-dominated, tropi- Glenn (1912) named the Baker Coal the Energy Shale, like the Dykersburg, to cal estuary or tidal delta having a small to for the Baker Mine in Webster County, crevasse splays and related environments moderate tidal range. Kentucky. Kosanke et al. (1960) gave the in a river-dominated deltaic setting simi- name Allenby Coal Member to a thin lar to the modern Mississippi (Johnson Baker Coal and Winslow- seam in southeastern Illinois. In southern 1972; Allgaier and Hopkins 1975; Nelson Indiana, geologists used the informal 1983; Palmer et al. 1985; Treworgy and Henderson Channel name Lower Millersburg coal. Our sub- Jacobson 1979; Burk et al. 1987). Archer The Baker Coal constitutes an important surface cross sections (unpublished) and Kvale (1993) pointed out flaws in economic seam in the southeastern demonstrate that the Baker, Allenby, and this model, including the absence of part of the Illinois Basin. The following Lower Millersburg coals are the same natural levees, the absence of unequivo- is a summary of information we have bed. Because Baker was the first name to cal evidence for crevasse splays, and the assembled from mine and borehole data. be used formally, we are using Baker Coal presence of a strong tidal signature. Their A longer report on the Baker Coal is in in this report. preparation. Illinois State Geological Survey Circular 605 51 HENDERSON 52 Bankston Fork Limestone (ft) (m) 0 0 10 Sha le 5 Brere na 20 ton Limestone An Energy Shale 30 10 blue band Herrin Coal 40 50 15 Springfield Coal Walshville channel Delafield Member Houchin Creek Coal Figure 42 Interpretive cross section of the Herrin Coal, Walshville channel, and Energy Shale. Charleston sby Ho rn Troy Quality Circle Sulfur (pounds per million Btu) 0 40 mi <0.6 Troy Mining District 0 60 km N 0.6 to 1.67 Walshville channel; no coal 1.67 to 2.5 Transitional roof >2.5 Extent of the Herrin Coal Figure 43 Map showing the Walshville channel and sulfur content of the Herrin Coal. After Treworgy et al. (2000). The four named areas of low-sulfur coal are all associated with thick Energy Shale adjacent to the channel. 53 aker o n limi t of B al itio n os Elkville outlier Cottage !GroveMine Crop line of Baker Coal Baker Mine! Figure 44 Map showing the Winslow-Henderson channel. Thick Baker Coal is largely restricted Fork (upper Providence) Limestone a Brackish to marine strata did not appear to narrow belts along a paleochannel short distance beneath the Baker Coal. until after the next younger major peat that was partly contemporaneous with The channel carved a valley 2 to 8 mi (3 to deposit, the Danville Coal. These obser- peat formation (Figure 44). Friedman 13 km) wide and as deep as 200 ft (60 m), vations suggest that (1) preserved Baker (1960) mapped this paleochannel in Pike removing units as old as the Springfield Coal developed farther up the coastal County, Indiana, and named it the Wins- Coal. Sandstone of the lower valley fill plain than did preserved Springfield Coal, low channel. Harper and Eggert (1995) displays large-scale lateral accretion on or (2) the sea level did not rise much fol- and Eggert (1994) extended the Winslow mine highwalls, signifying a meandering lowing Baker peat accumulation. channel farther south in the subsurface. system. Sandstone grades upward to finer Beard and Williamson (1979) mapped a grained, heterolithic strata that bear tidal paleochannel in Henderson and Web- rhythmites. Approaching the Wins- Danville Coal ster Counties, Kentucky, and called it low-Henderson channel, the Baker Coal The Danville (Figures 2 and 40) is the the Henderson channel. Because the thickens to 10 ft (3.0 m) or more, and it next major coal bed above the Baker. It Winslow and Henderson channels align has multiple laminae and thin interbeds is the youngest widespread, economi- directly at the state border, we recognize of carbonaceous claystone. The Baker is cally important seam in the Illinois Basin. them as the same feature and use the absent or reduced to stringers within a The Danville is thin and rather patchy compound name Winslow-Henderson meandering belt that varies from about 1 in western Illinois, reaching 3.3 ft (1 m) channel. to 3 mi (1.5 to 5 km) wide. thick in small areas. Coal thick enough to mine (generally 4 to 6 ft [1.2 to 1.8 m] Like the Galatia channel, the Winslow- The principal difference between the thick) is largely confined to a belt running Henderson comprises a broad, deeply Springfield and the Baker is that the latter north-northwest along the east side of the incised valley that was filled largely lacks marine roof strata and has no gray basin from Gibson County, Indiana, into with sand prior to peat development shale wedge analogous to the Dykers- northern Illinois. Coal-thickness patterns and a younger, narrower segment that burg. Covering the Baker is a succession (Korose et al. 2002) indicate that much of was filled with finer grained sediments of fluvial and floodplain deposits, includ- the thickest coal has been eroded east of during the time of Baker peat formation ing mudstone, thin lenticular sandstone, the present outcrop. Most Danville Coal (Figure 45). Borehole data and exposures thin coal, and paleosols. Lenses of gray has a high sulfur content, but low-sulfur in surface mines show that the channel shale a few feet (meters) thick bear fossil (locally <0.5%) coal occurs in Knox and cut downward from above the Bankston plants, including upright tree stumps. 5 4 Circular 605 Illinois State Geological Survey Dep Winslow-Henders Farmington Shale Danville Coal Lynnville Cottage Coal Baker Coal Baker Coal Providence (ft) (m) 0 0 Crown HR Mine mera Coal 10 ychannel H BR H R Winslow- 5 Henderson 20 channel 30 10 40 B H/BT BH/BT 50 15 SD/AC TM Dykersburg Shale Springfield Coal Figure 45 Interpretive cross section of the Winslow-Henderson channel. BR, Brereton Limestone; HR, Herrin Coal; BH/BT, Briar Hill/Bucktown Coal; SD/AC, St. David/Alum Cave Limestone; TM, Turner Mine Shale. Sullivan Counties, Indiana, and in the seam disruption that probably involved highly lenticular and has been less thor- bordering part of eastern Illinois (Harper peat rafting (Figure 46). However, no oughly studied than the other examples, 1988; Harper and Eggert 1995; Korose et channels contemporaneous with the so the relationship of coal to gray shale al. 2002). Danville have been encountered. and the channel is not completely under- stood. Overlying the Danville is a complex suc- Evidently, Knox County lay near the cession of gray clastic rocks that thickens mouth of a large estuary that discharged Jacobson (1983) documented that thick, from less than 3.3 ft (<1 m) in parts of sediment onto the Danville peat from the low-sulfur Murphysboro Coal in south- western Illinois to as much as 230 ft (70 east. Rapid burial under freshwater to western Illinois flanks a feature that he m) in the central Fairfield Basin of south- slightly brackish conditions resulted in named the Oraville channel (Figures 39 eastern Illinois. Where it is thin, the shale low-sulfur coal. Tidal currents agitated and 47). In fact, coal of mineable thick- is dark colored and, in places, is black, the peat near the estuary mouth, whereas ness (up to 8.2 ft [2.5 m]) is confined to a fissile shale similar to the Excello and deeper in the basin, the peat was quietly small area near the channel. Sulfur con- Turner Mine Shales. Eastward, the inter- buried under fine mud. tent is low to moderate (1% to 2.5%) near val changes to gray mudstone, siltstone, the channel where thick, nonmarine gray and sandstone arranged in multiple upward-coarsening cycles. The coarsest Murphysboro Coal and mudstone (unnamed) overlies the coal. Elsewhere, the coal is topped by marine facies occur in Knox County, Indiana, Oraville Channel black shale and limestone, and its sulfur coinciding with the only known area of The Murphysboro Coal, in the upper content is greater than 3% (Jacobson low-sulfur Danville Coal. Abundant fossil Tradewater Formation, presents some 1983). Away from the Oraville channel, plants, tree stumps in growth position, similarities to the Colchester, Springfield, the Murphysboro has a highly patchy and tidal rhythmites are much in evi- Herrin, and Danville Coals in that thick, distribution (Treworgy and Bargh 1984). dence in underground mines here. Rolls low-sulfur coal is associated with a gray Only small, isolated areas of thick coal are are also common, as are wedge-shaped shale “wedge” and a contemporaneous known. Little significant mining has taken siltstone splits and a large-scale coal- channel. However, the Murphysboro is place away from the channel. Illinois State Geological Survey Circular 605 55 0.30 m 1 ft Figure 46 Disruption of the Danville Coal, with the seam “split” by a thick wedge of mudstone. Note the ragged splaying of coal into mudstone, with a thin coal stringer crossing diagonally from the lower to upper “bench.” The site is the box cut at a portal of the Prosperity Mine in Gibson County, Indiana. The Murphysboro undergoes dramatic nature of “splitting” coal is poorly under- Model of Channel Development splitting near the Oraville channel mar- stood. Further study of the Murphysboro Our model is presented in 10 illustrated gins, where underclay is absent or weakly is required to integrate this unit into a stages (Figures 49 to 58). developed (Figure 48). Upright lycopsid general model. tree stumps are common above the lower coal bench. The gray mudstone exhibits Stage 1: Prograding Deltas tidal rhythmites and bears a prolific, well- DISCUSSION During Early Regression preserved flora dominated by Macroneu- Observations from mines and boreholes To set the stage, the Houchin Creek ropteris scheuchzeri, a plant believed to through the Galatia channel and related Coal, Excello Shale, and Hanover Lime- have been tolerant of coastal, perhaps features, as well as similar channels asso- stone sediments were laid down on a brackish-water, conditions (Falcon-Lang ciated with older and younger coal beds, tectonically stable platform from low- 2009). The Oraville channel follows the indicate that the old model of a Missis- stand (underclay and peat) through downthrown side of a monocline that was sippi-style delta having natural levees and rapid marine transgression to highstand active during deposition of the Murphys- crevasse splays is due for revision. Com- (black shale and limestone). During boro Coal (Nelson et al. 2011). bined with a better understanding and late highstand to early regression, clas- climate influences not available to earlier tic sedimentation resumed. A series of Ostensibly, the Oraville is another fluvial workers, these observations led to a new deltas were built into the basin, yielding channel that became an estuary, like the model of channel development that has upward-coarsening sediments of the Galatia and Walshville channels. How- connotations for larger concepts of cyclic Delafield Member (Figure 49). This part ever, nothing is known of the presumed sedimentation. of the model is similar to past cyclothem fluvial “precursor” channel, and the models in the Illinois Basin. 5 6 Circular 605 Illinois State Geological Survey R4W R3W R2W R1W T 4 S T 5 S T 6 S T 7 S T 8 S Coal thickness (ft) T 1.5–2.5 9 S 2.5–3.5 3.5–5.5 5.5–7.5 >7.5 T 10 S 0 3 6 mi 0 5 10 km Approximate coal outcrop or subcrop (after Shaw and Savage 1912; Smith 1958) Inferred outcrop or subcrop (after Shaw and Savage 1912) Oraville channel: sandstone and course-clastic fill; inferred, generalized boundaries Sandstone: coal missing; relationship to mapped portions of channel unclear Mined-out area Figure 47 Map showing the thickness of the Murphysboro Coal near the Oraville channel in Jackson and Perry Counties, southwestern Illinois. From Jacobson (1983). 57 Oraville channel 58 W E e) (ma rin e mes ton Oraville Li Creal Springs m ft tidal rhythmites 10 30 tree stumps abundan channel 20 t foliage 5 10 0 0 2–3 mi 3–5 km Figure 48 Interpretive cross section of the Oraville channel. Time Seasonal Climate Deltas prograde into basin Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Sea l evel Limestone Black shale Peat/coal Hanover Limestone Gray shale Excello Shale Houchin Creek Coal Sand/silt Conglomerate Figure 49 Stage 1: Deposition of the Delafield Member as a series of coalescing deltas during the onset of a glacial stage as the sea level began to fall. The product is a thick succession of clastic rocks that coarsen upward. Stage 2: Valley Incision and Stage 3: Aggradation and Gleying within the Galatia meander belt. This part Soil Development During Regression During Late Regression of the new model is similar to previous Delafield sediments rapidly filled avail- Channels developed broad meander models, although most treated paleosols able accommodation space in the basin. belts. As soon as the channel bottoms in a cursory fashion. With continuing marine regression, the were cut below sea level, suspended sedi- delta platform became exposed. Rivers ment (largely sand) began to drop out. Stage 4: Peat Initiation and cut downward to base level, creating Rivers reworked their own sandy depos- Paludification at Early Lowstand entrenched valleys. Given the extremely its. Valleys aggraded rapidly approaching Approaching glacial maximum or low- low gradient and the substrate of recently maximum lowstand, yielding an upward- stand, climate in the basin became deposited sediments, these streams fining profile (Figure 51). Approaching humid. Constant rainfall produced lush, actively meandered. Outside of valleys, maximum glaciation, climate in the Illi- dense vegetation, reducing sediment flux soil development was underway (Figure nois Basin became increasingly humid. and creating black-water rivers of mostly 50). Previous models (e.g., Potter 1962, This fostered vegetation growth, reducing plant tannin, clay, and perhaps a small 1963) placed channels in a deltaic set- soil erosion and sediment transport. bed load. Peat began to develop earli- ting and mostly did not take account of Increased rainfall leached iron from soils, est in low-lying areas on the landscape, eustasy, although Hopkins (1958) inter- gleying much of the upper soil profile such as abandoned meanders. Vegetation preted channels as being cut subaerially (Rosenau et al. 2013). Because of the lack lining the banks of the Galatia channel during regression and backfilled during of time and persistently wet conditions, stabilized the banks, locking meanders transgression. little or no soil formation took place into place for the duration of lowstand. Illinois State Geological Survey Circular 605 59 Time Seasonal Climate Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Soil formation (Veritsols) under a seasonal climate (wet/dry) Channel incision of exposed delta sediments River bank slumping Conglomerate lag at base of channel Limestone Black shale Peat/coal Gray shale Sand/silt Conglomerate Figure 50 Stage 2: Channel incision of delta sediments. Along the channel margins, fine clastics and Esterle 1993). Tectonic subsidence ment load. Silt carried down the Galatia infiltrated the peat swamp, perhaps by and concurrent peat compaction cre- channel was deposited beneath floating flocculation of clay in vegetated areas ated space for thick (albeit nondomed) peat layers, creating splits and major along channel margins. The result was peat deposits along the Galatia channel. seam disruptions. shaly coal in these channel-margin set- Placing coal at lowstand is conceptually tings (Figure 52). Previous Carbondale different from many peat or coal deposi- Stage 7: Estuarine Flooding cyclothem models did not incorporate tional models and is elaborated on in the During Early Transgression syndepositional channels. following section. Melting induced rapid, pulse-like trans- gression, drowning the Springfield peat Stage 5: Widespread Peat Stage 6: Peat Rafting and Splitting swamp first along the Galatia channel, Accumulation at Lowstand During Initial Transgression which became an estuary (Archer et al. Peat development overspread the basin Glaciation ended abruptly as the polar 2016). The tropical climate became drier except for active channels and well- climate warmed. During the initial stages and more seasonal, which reduced the drained tectonic highs (Figure 53). Natu- of sea-level rise, the lower part of the vegetation cover upstream, enhancing rally, the thickest peat accumulated in the Galatia channel was subjected to increas- runoff, erosion, and fluvial sediment lowlands flanking the Galatia channel. ingly vigorous tidal ebb and flow (Figure transport. A heavy load of gray silt (Dyk- Periodic floods brought fine silt and clay 54). Buoyed by trapped air and self- ersburg Shale) rapidly overwhelmed the out into the swamp, creating clastic lami- generated methane, large mats of peat peat, entombing tree stumps and other nae in the peat close to the channel. This floated free of the substrate. At the same plant remains in place (Figure 55). Some process is taking place today along the time, the climate shifted from ever-wet to Dykersburg sediment might have been Rajang River in Sarawak, Malaysia, where wet–dry seasonal. This led to less vegeta- derived from offshore and carried up the domed peat deposits fringe the river tion cover in inland source areas and a estuary by tidal currents, as is happening under a tropical, ever-wet climate (Staub consequent increase in runoff and sedi- today in the Kampar River of Sumatra, 6 0 Circular 605 Illinois State Geological Survey Time Seasonal Climate Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Soil formation—wetting climate strips iron, turning soils gray Meander valley Incised valleys accumulate local and transported sediment Limestone Black shale Peat/coal Gray shale Sand/silt Conglomerate Figure 51 Stage 3: The Galatia channel developed a meander belt. which is located just north of the equator ended when the basin area became so was high and carbonate deposition took under perhumid conditions. The upper deep and far offshore as to be beyond the place as the St. David Limestone (Figure Kampar has a deep channel and tea- realm of coastal processes. 58). Continued clastic influx during high- colored water that carries practically no stand led to delta progradation (Canton bed load or suspended sediment. Cecil Stage 9: Black Shale of Late Shale), ending carbonate production and et al. (2003a, p. 32) wrote, “The lower 85 Transgression and Highstand beginning the next cycle. This process is km [52.8 mi] is exceedingly shallow and similar to those in previous models. difficult to navigate even in small boats The Turner Mine Shale records rapidly of very shallow draft” because of the deepening water. The water column strat- sediment carried up the estuary by the ified, bottom circulation ceased, and the Linkage of Climate and Eustasy tides. Placing the Dykersburg in a tidal– Illinois Basin became sediment starved. We have alluded to changes in climate, estuarine facies puts this relatively new Fine sediment that filtered down resulted together with fluctuating sea level, as concept into the larger cyclothem model in black, phosphatic shale (Figure 57). being instrumental in the evolution of and emphasizes the coastal–estuarine Our model is similar to previous ones, the Galatia channel and its related fea- rather than the deltaic nature of this part such as those of Heckel (1977, 1986, tures. The recurrent glacial episodes that of the cycle. 1994). induced sea-level changes affected cli- mate in the tropical realm of peat produc- Stage 8: Estuary Advances Stage 10: Limestone Deposition tion as well as in the polar and temperate Inland as Regression Continues at Highstand to Early Regression realms. Here we explore how and why cli- At maximum deglaciation, the sea level mate and sea-level changes were linked.Loaded with sediment, peat compacted rapidly, making space for more sediment. crested and the climate was seasonally Earth’s climate belts of today are the Basin subsidence, sea-level rise, and peat dry. During highstand, bottom circula- products of unequal solar energy to the compaction worked in concert until more tion became reestablished. Because the earth’s surface. Solar radiation is most than 98.4 ft (>30 m) of Dykersburg Shale climate was seasonally dry, evaporation intense in the tropics, where the sun is was in place (Figure 56). The process Illinois State Geological Survey Circular 605 61 Time Seasonal Climate Soil formation—ever-wet climate Estimated Sea Level drowns landscape, Histosols develop Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Low areas on landscape develop peat first and spread outward Channel margins accumulate peat early, constrain channel migration, locking banks in place Se d du ie m t eo n d t-e pLimestone n os oe r rv ie veg r Black shale etation Peat/coal Gray shale Sand/silt Conglomerate Figure 52 Stage 4: The change to a humid climate caused the Springfield peat to begin to form. directly overhead. Hot air rises in a belt summer2 and south in winter. The result fixed in place during glacial episodes, that girdles the earth roughly parallel is that many areas of the tropics receive much of the equatorial region experi- to the equator. Rising air, heavily laden distinct wet and dry seasons. Wet seasons enced an ever-wet climate. with moisture, cools as it rises, produc- or monsoons, characterized by torrential ing clouds and heavy rainfall. This rainy downpours, take place when the ITCZ is Plate-tectonic reconstructions indicate tropical belt of rising air is called the overhead. Monsoons alternate with hot, that during the Pennsylvanian, the coal- intertropical convergence zone (ITCZ). In dry seasons when little rain falls. Depend- forming regions of the Illinois and Appa- more familiar terms, this is the doldrums, ing on the local geography, areas of the lachian Basins, maritime Canada, West- that zone of light and fickle winds where tropics may receive either one or two ern Europe, Russia, and the Ukraine were sailing ships often lay becalmed for weeks annual monsoons, whereas other places all aligned close to the equator. Thus, a at a time. The ITCZ is also a belt of low have an ever-wet (or perhumid) climate, number of authors (Cecil et al. 2003a, pressure that draws air from both north under which rainfall exceeds evapotrans- 2003b; Peyser and Poulsen 2008; Eros et and south, setting up persistent winds piration every month of the year. al. 2012; Horton et al. 2012) deduced the that angle toward the equator—the trade following equation: winds. Beyond them lie the horse lati- In the modern world, cold, dense air tudes, which, like the doldrums, are belts settles over the poles and flows outward, Maximum glacial ice = Low sea level = Ever- wet climate = Maximum peat production. of persistent high pressure, light and vari- displacing warm, moist air and generat- able winds, and dry weather (Figures 59 ing storms in the middle latitudes. During Conversely, during the interglacial epi- and 60). Most of the earth’s largest deserts the “ice ages,” the polar realm expanded sodes, the sea level rose and a monsoonal fall in the horse latitudes. greatly, compressing the earth’s other cli- regime of pronounced wet and dry sea- mate belts toward the equator. As a result, sons took hold. Less vegetation stabilized The doldrums (ITCZ), trade winds, and the ICTZ did not migrate as freely with the landscape because fewer plants could horse latitudes follow the sun through the seasons as it does during the current tolerate the extended annual droughts. the seasons, migrating north during the interglacial episode. With the ITCZ nearly Hence, soil erosion and the sediment 2For simplicity, seasons are discussed in northern hemisphere terms. 62 Time Seasonal Climate Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Peat envelops the landscape Springfield peat Channel margin peat gets periodically flooded, depositing thin, dark, silty clay layers Sedim Limestone ent-poor ri Black shale ver Peat/coal Gray shale Sand/silt Conglomerate Figure 53 Stage 5: Springfield peat accumulates across a large area of the basin. load in streams increased dramatically oped in domed or raised mires, which Rapid Transgression, Gradual compared with the episodes of ever-wet excluded clastic sediment derived from Regression climate, when plants carpeted the land- nearby rivers. scape: Evidence from the Pleistocene, par- However, evidence from coal-body geom- ticularly the most recent deglaciation, Minimum glacial ice = High sea level etry, coal petrography, geochemistry of indicates that melting can be surprisingly = Strong wet–dry seasonal climate = coal and enclosing strata, and fossil-plant rapid, even “catastrophic.” Blanchon Maximum erosion and runoff. patterns strongly suggests that Desmoine- and Shaw (1995, p. 4) inferred, based on sian coal in the Illinois Basin developed drowned reefs in the Caribbean and Gulf Peat Developed at Lowstand as planar, not domed, peat deposits (Cecil of Mexico, “three catastrophic, metre- et al. 1985; Eble et al. 2001; Greb et al. scale sea-level–rise events during the last Our model calls for the Springfield Coal 2002, 2003; Neuzil et al. 2005). Thus, peat [Pleistocene] deglaciation.” Gregoire et (and, by implication, other Pennsylva- accumulated at grade with the Galatia al. (2012) calculated that a sea-level rise nian coal seams) to be formed during channel, with plants filtering clastics of 45.9 to 59.0 ft (14 to 18 m) took place eustatic lowstand under ever-wet con- through the flanking belts now preserved within a span of about 350 years close ditions. Some previous authors, such as shaly coal. The Galatia was a river to 14,000 years ago, and a rise of 29.5 ft as Flint et al. (1995), Bohacs and Suter without banks or natural levees. Peren- (9 m) took place within 500 years about (1997), and Heckel (2008), maintained nial flooding from the channel, coupled 8,200 years ago. Data from Greenland ice that peat developed during transgres- with an ever-wet climate, ongoing basin cores indicate two remarkably sudden sion. According to their view, preserving a subsidence, and ongoing compaction of Late Pleistocene warming events. One at thick peat deposit requires a rising water underlying sediment, maintained a con- 11,700 years B.P. lasted 60 years, and an table because otherwise peat is oxidized sistently high water table throughout the earlier event at 14,700 years ago spanned and lost. Flint et al. (1995) further held duration of Springfield peat accumula- a mere 3 years (Steffensen et al. 2008). that most economic coal deposits devel- tion. Other evidence and examples may be Illinois State Geological Survey Circular 605 63 Time Seasonal Climate Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Increasing seasonality decreases vegetation density inland, allowing sediment into drainages and rivers Channel margin peat is ripped by tides, winnows away interlaminated muds, leaving peat flaps. Flaps float upward in response to trapped gas in peat. Repeated vertical movement from tides peels peat away in sheets; gaps are infilled by mud and silt, creating channel-adjacent splits. Tidal amp C d le assh ci r ti e ca -rft to s ic in h g r v is veLimestone ea eg r s don ea ta u t eio to Black shale l clim na ,te Peat/coal Gray shale Sand/silt Conglomerate Figure 54 Stage 6: A warming climate brought rapid melting of the glaciers and a sea-level rise. The Galatia channel became an estuary, subject to strong tidal currents. found in Webster et al. (2004), Wright et nental glaciers is “glacially slow” because lack channels and a gray shale roof. Most al. (2009), Bird et al. (2010), and Törn- snow and ice can accumulate only so commonly, the coal is sharply overlain qvist and Hijma (2012). In contrast, the fast. In fact, the global cooling required to either by offshore black, phosphatic growth of a continental ice cap requires a bring on an ice age reduces the capacity black shale or by marine limestone; at much longer interval of time, measured of the atmosphere to hold water vapor the contact, coal laminations are gener- in thousands to tens of thousands of and yield snow. ally truncated, indicating some erosion years (Muhs et al. 2011; Dutton and Lam- of the top of the peat body. At the base beck 2012). The rapid drowning and burial of the of black shale, a thin pyritic shell breccia Springfield peat swamp has counterparts may be present (Zangerl and Richardson The authors cited above suggest that any in other late Paleozoic deposits. Ravine- 1963). Where nonmarine gray shale over- triggering event that raises the sea level ment surfaces are reported from other lies low-sulfur coal, in situ tree stumps may set off a chain of events leading to coals, such as the Herrin Coal of Illinois and tidal rhythmites are commonly in the rapid destruction of ice caps. The (DeMaris et al. 1983), which also has a evidence. We have logged examples, trigger could be the onset of a warmer buried autochthonous flora adjacent to including the Lower Block, Murphysboro, climate or the failure of ice dams that the Walshville paleochannel (DiMichele Colchester, Herrin, and Danville Coals in hold back large bodies of fresh water, and DeMaris 1987). Lower Permian addition to the Springfield. such as glacial Lake Agassiz and Lake carbonate cycles of Kansas commonly Missoula. The rising sea breaks up float- begin with a thin transgressive lag of fish Conditions of rapid, pulse-like sea- ing ice sheets and releases fleets of ice- bones, ostracods, and intraclasts, imply- level rises likely also occurred during bergs, which melt in warmer waters and ing abrupt, erosive transgression (Miller the Pennsylvanian ice age (Archer et raise the sea level further. Moreover, the et al. 1996). The rapid marine transgres- al. 2016). Such considerations further loss of sea ice changes the ocean and sion that terminated peat accumulation militate against the notion of “keep up” atmospheric circulation, leading to more repeats throughout the Pennsylvanian in time-transgressive peat swamps created melting. In contrast, the growth of conti- the Illinois Basin among coal beds that by rising base level and driven across the 6 4 Circular 605 Illinois State Geological Survey Time Seasonal Climate Peat ripping and peat lifting . from tidal action mpTidal a Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Rolls fill with tidal sediment, covered by prograding sediment Gray shale thicker close to channel, more rapid deposition close to channel Estuary brack ish resh to F Filling Limestone estuary Black shale Peat/coal Gray shale Sand/silt Conglomerate Figure 55 Stage 7: Peat swamps drowned as the estuary became an embayment. Dykersburg sediments rapidly buried the peat. landscape by sea-level rise (e.g., Heckel (Figure 61) falls between the major Lower We propose the following scenario: 1995). Peat formed much too slowly to Fort Scott (Excello Shale) and Upper Fort During late highstand and early regres- keep up with the abrupt sea-level rise of a Scott (Little Osage Shale, correlative with sion of the major Lower Fort Scott typical deglaciation. Turner Mine Shale) cycles (Heckel 1994, cycle, deltaic sediments of the Delafield 2002, 2013). As Heckel (2002, p. 110) Member essentially filled the Illinois Relationship of the Effingham stated, “The upper part of the Blackjack Basin. As the sea level continued to fall, Creek Limestone extends as a bed into the Effingham channel became incised and Galatia Channels the upper part of the Morgan School and established a meander belt. Then The Effingham channel clearly was cut, Shale in Iowa, where it contains mod- came the minor Upper Blackjack Creek filled, and abandoned prior to develop- erately abundant conodonts [and] thus transgression, drowning the Effingham ment of the Galatia channel. In fact, the apparently represents a minor transgres- channel and backfilling it with sediment. Galatia channel crosses the Effingham sion.” Heckel further noted that “the When sea level again declined, a new at a right angle. Thus, the two channels Lower Fort Scott cyclothem loses both its fluvial system—the Galatia channel— represent separate cycles of sedimenta- lower and upper bounding paleosols a became established on the exposed shelf. tion. Previously, all strata between the short distance south of the Kansas border No limestone or marine fossiliferous Houchin Creek and Springfield Coals in northern Oklahoma [see Heckel 2013, shale marks the Upper Blackjack Creek were assumed to belong to a single cycle figure 11, p. 20]. This supports the idea event in this basin because the sea-level (Summum cyclothem), reflecting a single that the lower part of the Midcontinent rise was relatively brief and low in ampli- episode of marine transgression and shelf in southern Kansas and northern tude. Tidal rhythmites in the upper Eff- regression. Oklahoma was at a lower Pennsylvanian ingham channel fill in the Elysium core, elevation than the entire Illinois Basin” and local, thin coal in other boreholes In the Midcontinent Basin, the correla- (P.H. Heckel, written communication to points to estuarine conditions, not fully tive interval contains two cyclothems. W.J. Nelson, June 6, 2014). marine. The minor Upper Blackjack Creek cycle Illinois State Geological Survey Circular 605 65 66 Time Seasonal Climate Margins of gray shale bodies get eroded, Estimated Sea Level carving out mud islands. Landscape Elevation of the Black shale infills area Illinois Basin 300 m.y.a. (Per)humid Climate Black shale implies anoxic water. Organics in shale trend from terrestrial at base to marine at top. Black shales pinch out against the flanks of the big gray shale body evel Sea L Limestone Black shale Peat/coal Gray shale Sand/silt Conglomerate Figure 56 Stage 8: As the transgression continued apace, the entire basin area was submerged in deep water, which became stratified and anoxic, and black mud (Turner Mine Shale) was deposited. Time Seasonal Climate Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Gray shale wedge, Sea level rises, coastlines get former estuary pushed inland, and sediment depocenters follow. Water column clears and Limestone pinches out against the conditions become favorable flanks of the big gray shale body for limestone, blanketing the black shales. level Sea Limestone Black shale Peat/coal Gray shale Sand/silt Conglomerate Figure 57 Stage 9: Normal marine circulation resumed near the apex of an interglacial stage (marine highstand), bringing a brief interlude of carbonate sedimentation (St. David Limestone). As an alternate hypothesis, an autocyclic ently repeating sequences of lithologies similar features in other coals, only serve process or tectonic movement in the in coal-bearing rock sections of Penn- to strengthen the argument for a periodi- basin might have led to the abandon- sylvanian age (Langenheim and Nelson cally repeating class of natural phenom- ment of one channel (Effingham) and the 1992). These authors tied such succes- ena as drivers of lithological sequences in establishment of another (Galatia) during sions to sea-level fluctuations driven by Pennsylvanian cratonic coal-bearing rock a single eustatic cycle. Earth movements the waxing and waning of polar glaciers sequences. The relatively recent additions might have changed the regional gradient during the Pennsylvanian, a model that of climate (e.g., Cecil et al. 2003a, 2003b; from southeast to southwest, inducing a has proven remarkably robust and con- Horton et al. 2007; Peyser and Poulsen change in channel orientation. This idea tinues in use today (e.g., de Wet et al. 2008; Bishop et al. 2010) and of the ties is not farfetched because both the Spring- 1997; Heckel et al. 2007; Heckel 2008; between climate and sedimentation pat- field and Herrin Coals thin across the Eros et al. 2012; Waters and Condon terns (Cecil and Dulong 2003) provide a La Salle Anticlinorium and other basin 2012). Challenges to the cyclothem con- more complete framework for explaining structures, indicating syndepositional cept reflect various attempts to outright cyclothemic patterns in space and time, tectonism. The channel-forming process discredit it (e.g., Wilkinson et al. 2003), particularly those permitting escape from clearly was complex and required a sub- to demonstrate control by local, coastal an either–or focus on allocyclic versus stantial amount of time. sedimentary processes (e.g., Horne et autocyclic underlying controls (in the al. 1978; Ferm and Cavaroc 1979) or terminology of Beerbower 1964) while CHANNELS AND by structural geological movements recognizing the role and context of each.(e.g., Ferm and Weisenfluh 1989), or CYCLOTHEMS: A SUMMARY to subsume it terminologically within The modern cyclothem concept takes MODEL sea-level-driven sequence stratigraphic full account of sequence stratigraphy, models (e.g., Bohacs and Suter 1997). including autocyclic processes, such as Wanless and Weller (1932) introduced The recurrent patterns discussed here, the formation of deltas, within a frame- the term “cyclothem” to describe appar- in relation to the Galatia channel and work of sea-level change. The proximate Illinois State Geological Survey Circular 605 67 Time Seasonal Climate Estimated Sea Level Landscape Elevation of the Illinois Basin 300 m.y.a. (Per)humid Climate Sea level slowly falls, coastlines build seaward, and sediment depocenters push basinward. Deltas prograde covering coal, gray shale, black shale, The next cycle begins limestone. el Sea L ev Limestone Black shale Peat/coal Gray shale Sand/silt Conglomerate Figure 58 Stage 10: Marine regression begins the next cycle. A–A′ cross section ITCZ (doldrums) Open ocean and eperic seas Land Surface winds Figure 59 Conceptual model of Pangea during a glacial episode of the Pennsylvanian. From Cecil, C.B., F.T. Dulong, R.R. West, R. Stamm, B. Wardlaw, and N.T. Edgar, 2003b, Climate controls on the stratigraphy of a Middle Pennsylvanian cyclothem in North America, in C.B. Cecil and N.T. Edgar, eds., Climate controls on stratigraphy: SEPM Special Publication 77, p. 151–180. Copyright © 2003, used with permission of SEPM; permission conveyed through Copyright Clearance Center, Inc. ITCZ, inter- tropical convergence zone. A–A′ cross section ITCZ a Open ocean and eperic seas Land Surface winds A–A′ cross section ITCZ b Open ocean and eperic seas Land Surface winds Figure 60 Conceptual model of Pangea during an interglacial episode of the Pennsylvanian. From Cecil, C.B., F.T. Dulong, R.R. West, R. Stamm, B. Wardlaw, and N.T. Edgar, 2003b, Climate controls on the stratigraphy of a Middle Pennsylvanian cyclothem in North America, in C.B. Cecil and N.T. Edgar, eds., Climate controls on stratigraphy: SEPM Special Publication 77, p. 151–180. Copyright © 2003, used with permission of SEPM; permission conveyed through Copyright Clearance Center, Inc. ITCZ, intertropical convergence zone. driving force of Pennsylvanian and Early et al. 2010) and whether it was present Pangaea. We will take as a given that Permian sea-level change still appears at all (Fielding et al. 2008; Gulbranson cyclothems reflect covariant changes in to be changes in grounded ice volume, et al. 2010) during some intervals of the sea level, climate, and sediment transport mainly in the south polar and moun- Pennsylvanian (such as the Kasimovian; volume linked to variations in ice volume tainous regions of Gondwana. However, e.g., see Gulbranson et al. 2010), during (Horton et al. 2007, 2012). questions have been raised about the which cyclothemic sequences nonethe- sufficiency of the volume of ice (Isbell et less continue to be found in the equato- There also are elements that, although al. 2003; Horton and Poulsen 2009; Henry rial regions of central and west-central varying through time, must be treated Illinois State Geological Survey Circular 605 69 ILLINOIS Turner Mine Shale MIDCONTINENT Springfield Coal Little Osage Shale Galatia Summit Coal Upper Blackjack Delafield Creek equivalent? Effingham upper Blackjack Creek Limestone lower Excello Shale Hanover LimestoneExcello Shale Mulky Coal Houchin Creek Coal Not to scale Figure 61 Diagram illustrating the possible relationship of the Effingham and Galatia channels to Midcontinent cyclothems. as constants because (1) they are not torial Pangaean cratonic surface allowed face (a ravinement surface). Above this linked causally to the set of variables for widespread, nearly synchronous surface, there may be discontinuously tied to cyclic global change, and (2) their deposition of many marine units and distributed phosphate nodules (Heckel effects and timing are often obscure. The equally for the widespread development 1977), signifying a period of sediment most prominent of these is tectonics. It is of soils on exposed surfaces, including starvation under marine water cover, or understood that accommodation space is Histosols (peats), under conditions of a thin, discontinuous marine bed, often needed to preserve sediments as part of widespread, aseasonal to weakly seasonal just a shell hash (Bauer and DeMaris the geological record. However, remark- patterns of high rainfall. 1982), what Heckel (1986) has called ably robust correlations have proven the transgressive limestone. Above the possible between cyclothemic, glacial– The terrestrial portion of a cyclothem ravinement surface, and transgressive interglacial cycles in the cratonic basins consists primarily of a mineral paleo- limestone, if present, is generally a wide- of the American Midcontinent (Western sol, developed on normal marine or spread, sheety black shale that, where Interior), Illinois (Eastern Interior), and near-shore marine deposits, followed by it has been examined, has a terrestrial Appalachian regions (Heckel et al. 2007; patchy to widespread mineral swamp organic signature in its lower half and a Falcon-Lang et al. 2011), correlative with deposits, represented by organic-rich marine signature in its upper half (James a nearly identical cycle sequence in the shales and terminated by a Histosol, and Baker 1972; Banerjee et al. 2010). This Donets Basin (Heckel et al. 2007; Heckel developed in a peat-forming environ- black shale often contains marine inver- 2008; Eros et al. 2012; Schmitz and Davy- ment. The contacts between these units tebrates throughout. Succeeding and in dov 2012; Davydov et al. 2012), based can be sharp or gradational. The basal sharp contact with the black shale is a on marine microfossils, palynology, and paleosol, particularly in the later Middle marine limestone that contains a normal radiometric dating. These correlations Pennsylvanian and Late Pennsylvanian, marine fauna. Above this limestone, vari- reveal that nearly every major cycle and and in some places, earliest Permian, ably developed is a sequence of mixed many minor cycles are preserved in all shows strong evidence of a complex gray shales and sandstones that generally these basins. This high degree of correla- origin. Such paleosols are vertic and often coarsen upward and rarely can contain tion leads to the conclusion that the cre- calcic, evidencing a seasonal climate thin, discontinuous layers or beds of ation of accommodation space was suf- and well-drained conditions during their organic-rich shale or coal. In most cases, ficient to be treated, on average, as a con- early formation. These initial patterns these deposits appear to be of deltaic stant, even though there clearly are local are overprinted by evidence of decreas- origin and strongly reflect autocyclic con- effects on the thickness or areal extent of ing seasonality and increasing moisture, trols on local characteristics. The paleosol any given bed, as discussed above. during which the soil was gleyed to at the base of the terrestrial portion of various degrees. Mineral soil formation the next sequence is developed upon terminates with surface flooding, locally The “Typical” Cyclothem on a these marine to brackish-water deposits. with the development of clastic swamps The parent material of the soil may vary Cratonic Platform and finally with the onset of peat forma- considerably, reflecting the landward tion (Joeckel 1995, 1999; Miller et al. 1996; A Midcontinent North American extent and depth of the transgression that Cecil et al. 2003a, 2003b; Hembree and cyclothem, at its simplest, consists of accompanied the previous interglacial Nadon 2011; Catena and Hembree 2012; a terrestrial and a marine portion. The and associated sea-level highstand. Rosenau et al. 2013). rock units representing these markedly This characterization of a cyclothem is a different settings are, in most cases, not The contact between the terrestrial and generalization. Details of how this series interdigitated. The great flatness and large marine portions of the cyclothem is of terrestrial–marine environments is areal extent of the central-western equa- marked by an often-cryptic erosional sur- represented in the rock record depend 7 0 Circular 605 Illinois State Geological Survey strongly on vagaries in a number of physi- was exposed during sea-level fall, in the have been explained as reflections of tec- cal variables. These include the extent early stages of glacial advance. As a con- tonism, again holding climate constant of marine transgression, the maximum sequence, the development of paleosols (e.g., Wanless 1964). There certainly are water depth, the volume of sediment and and floodplain deposits likely began channels at many portions of any glacial– location of sediment delivery points, the under the strongly seasonal subhumid interglacial cycle, but these must not be rate of sea-level rise and fall, the length of climates to, in some instances, even semi- confused as being of a single type or all the exposure period of the craton during arid climates that characterized sea-level reflecting deposition under a common falling sea-level stages and at lowstand, highstands and falling stages (Cecil set of circumstances. the length of time and extent over which et al. 1985, 2003a, 2003b; Peyser and the tropical climate was suitable for Poulsen 2008; Tabor and Poulsen 2008; Lowstand channels are partially con- peat formation during lowstand, and, of Horton et al. 2012). The flatness of the temporaneous with the paleosols that course, the rate amount of and areal vari- craton in the Midcontinent through the underlie coal beds, and these paleosols ability in the creation of accommodation Appalachian Basin must be kept in mind are indicators of the climatic conditions space. That regular cycles can be recog- here. By the late Atokan, land-surface under which the precoal channels and nized at all, given the many variables, irregularities created by the Mississip- floodplains formed (Feldman et al. 2005; shows the strong influences of the most pian–Pennsylvanian sea-level drop had Falcon-Lang et al. 2009). Such paleosols basic drivers, climate and eustasy, which filled such that the surface of the craton, may have thicknesses of up to several feet overprint the entire record, allowing for deeply incised at the end of the Missis- (meters) and characteristics that include the creation of accommodation space. sippian (Howard 1979; Kvale and Archer indicators of seasonality of moisture or 2007), had become much flatter (Waters rainfall (vertic features), even consider- Cyclothem Models Do not and Condon 2012). This flatness is the able periods when evapotranspiration major factor that led to beds of huge areal exceeded rainfall (the development of Address Contemporaneous extent, contemporaneous throughout soil carbonates—which, in older litera- Channels their extent, most notably coals (e.g., ture, often were referred to as “fresh- water” carbonates and envisioned to The traditional cyclothem model leaves Greb et al. 2003) but also open marine environments (Heckel 2008) and fossil have formed in lakes, laterally equivalent out the channel deposits that form contemporaneously and continuously soil horizons (Cecil et al. 2003a, 2003b). to marine limestones offshore; e.g., see Consequently, with the shelf edge of the Wanless 1964). The climate signature of through the interval of paleosol develop- these sorts of paleosols stands at odds ment, peat formation, and early sea-level mid-Pangaean equatorial craton in the modern-day Arkoma Basin region of with the coal beds that immediately rise. Also left out along with these chan- nels, and of particular interest here, are Oklahoma by later Middle Pennsylvanian supersede them stratigraphically. Formed (Desmoinesian/Moscovian), slopes on as Histosols, the coals are indicative of the gray-shale wedges that lie immedi- ately above, and in gradational contact the surfaces leading inland from that perhumid to humid climates (humid during the later Middle and Late Penn- with, the coal bed along the channel point may have been much less than 6.3 flanks, the splits in the coal bed that form in./mi (<10 cm/km). As a consequence sylvanian; perhumid during much of the earlier Pennsylvanian—see Cecil contemporaneously with final channel of this low slope, exposure of the cratonic surface during sea-level fall, or its flood- et al. 1985; Cecil and Dulong 2003). As filling, and the dark shales interbedded the glacial maximum was approached with the coal close to the channel. These ing during sea-level rise, was likely rapid. Once the slow process of ice buildup (sea-level lowstand), the climatic sea-deposits, which reflect the complex inter- action of allocyclic (sea level and climate began during the early phases of a gla- sonality under which these soils initially developed began to diminish, resulting in particular) and autocyclic processes, cial interval, small changes in sea level would have had large effects on the depth in an overprint of a wetter climate state are key indicators of the timing of peat or coal formation during a glacial–intergla- of water coverage on the craton and the (Cecil et al. 2003a, 2003b; Hembree and Nadon 2011; Rosenau et al. 2013). cial cycle. Such deposits appear to have timing and extent of surface exposure. This late-stage increase in rainfall and existed contemporaneously with every The channels and associated deposits dis- decrease in seasonality, while soils were major coal bed, to have been expressed cussed here are those that were initiated still well drained, led to the initiation of differentially depending on the many fac- on the exposed cratonic surface during organic buildup on the soil surface, with tors described briefly above, and to have falling stages of sea level and that contin- the attendant formation of weak organic been known or understood to different ued uninterrupted through early stages acids and the subsequent intense gleying degrees in each instance depending on of sea-level rise. Attempts to incorporate that characterizes so many Pennsylva- the availability of exposures, both natural dynamics into the cyclothem model nian paleosols in coal-bearing sequences and created, by mining and road con- often place channels throughout the (Joeckel 1995, 1999; Cecil et al. 2003a, struction or in drill core. entire sequence (e.g., Baird and Shabica 2003b; Driese and Ober 2005; Hembree Perhaps the most important aspect of 1980; Jacobson 2000), relying on a strictly and Nadon 2011; Rosenau et al. 2013). the channel deposits is their long dura- autocyclic, deltaic model of deposition With continued high rainfall and greater tion, within the framework of a glacial– for an entire cyclothem under an invari- interglacial cycle. As can be seen from ant climate (e.g., Horne et al. 1978). Gray uniformity of moisture distribution shale clastic wedges covering coal beds, throughout the year, the formation of the examples discussed above, stream and associated with channel deposits, swampy surface conditions ensued across downcutting began as soon as the craton much of the low-gradient, widely exposed Illinois State Geological Survey Circular 605 71 craton, leading to the development of and Poulsen 2008) and the relationship deposits, reflecting the rising sea levels peat swamps. The coal beds resulting between climate and sediment transport of the current interglacial. Additionally, from these peat swamps were not time patterns (Cecil and Dulong 2003). The fill- it should be considered that during the transgressive; they did not form as narrow ing of the main channel course with clas- Pennsylvanian, there was no peat or coal belts, moving inland ahead of rising sea tic material is accompanied also by the in vast expanses of the western Pangaean level, as is often portrayed (e.g., Heckel erosion of the margins of the peat body, tropical or equatorial regions, which 1995; Bohacs and Suter 1997), but were resulting in a series of floating peat mats many climate proxies indicate was under time equivalent over large areas (Greb (Elrick et al. 2008), between which clastic a strongly seasonal climate regime too et al. 2003), as indicated by such evi- material was deposited, resulting in the dry for peat formation. Were sea level dence as ash partings (Greb et al. 1999), “splits” that line the contact between the the driver, peat should be equally pres- widespread clastic partings that fall at coal body and the contemporaneous, ent throughout all coastal belts across consistent levels within the coal bed over now estuarine, and strongly tidally influ- the Pennsylvanian and Permian world, its whole extent, or partings that separate enced channel. regardless of the prevailing climate. This benches of coal with distinct petrographic is clearly not the case. characteristics throughout their areal extents (Eble et al. 2006). As discussed The Gray-Shale Wedge and Its This model is supported further by evi- above, channels already present on the Relationship to the Channel dence for low-sediment to black-water landscape were considerably narrowed conditions in major peat-contemporane-It is important to recognize that eco- by the development of erosion-resistant ous drainages. Sediment transport within nomically mineable, low-ash, and low- to peat deposits on their floodplains and channel systems is, of course, tied directly moderate-sulfur blanket coals intrinsi- along their banks. In addition, intense to the entry of sediment into drain-cally have nothing to do with sea level as plant rooting acted to stabilize the local age systems. As discussed by Cecil and the driving force of their formation (Cecil substrate and greatly reduce sediment Dulong (2003), on the basis of empirical et al. 1985). The peats from which these input to streams throughout the drain- observations in modern tropical environ-coal beds formed reflect the climate, age basins on these very flat landscapes. ments, high rainfall distributed through-specifically humid to perhumid climatic Channels such as the Galatia channel, the out the year results in densities of plant conditions (terminology from Cecil and Walshville channel, the Oroville channel, cover that stabilize soils and drastically Dulong 2003) covering large areas of the and others share the common charac- cut back on sediment movement into paleotropics. Such climatic conditions teristic of being significantly narrower streams. With the melting of ice during can occur, hypothetically, at any point and showing no evidence of the dynamic the glacial–interglacial transition, major in space and time. However, because character of their precursors on clastic changes in atmospheric circulation of the various extrinsic drivers, most floodplains. In addition, at this stage the patterns (e.g., Cecil et al. 2003a, 2003b; proximately related to ice volume and rivers appear to have carried little sedi- Peyser and Poulsen 2008; Horton et al. atmospheric CO (Horton et al. 2012), 2 ment other than very fine grained mate- 2012) led to increasing seasonality in the the peat swamps that became coals are rial or dissolved organic matter. Floods tropics (Kvale et al. 1994). This change mainly confined to the lowstand phase carrying this material into the adjacent led directly to a reduction in vegeta-of the covariant, linked sea-level and peat swamps created the abundance of tional cover, particularly in those areas climate cycles (Cecil et al. 2003a, 2003b), fine, dark, thin laminae of clastic material surrounding the coastal peat-swamp thus around the time of maximum glacial that is found in coal beds adjacent to the ecosystems, resulting in an influx of clas-conditions. coal-contemporaneous channels, sug- tics into drainages. This clastic influx is gesting low-sediment to black-water river For interpretation of the position of coal thus coincident with rising sea level and conditions. within a sea-level rise–fall cycle, the rate the initial conversion of river drainages of sea-level rise, and the timing of sedi- into estuarine environments. Under this In their final stages, the coal-contempo- ment emplacement within the channel, model, the sediment that blanketed peat raneous reaches of cratonic river systems the gray-shale wedge is probably the swamps adjacent to major drainages orig- appear to have become estuarine and single most important feature within a inated coincidently with rising sea level, tidally influenced (e.g., Archer and Kvale cyclothemic sequence. melting ice, and climate changes from 1993; Tessier et al. 1995) and to have humid–perhumid to wet subhumid, and widened considerably through disrup- As discussed above, we believe the progressively to dry subhumid. Carried tion of the peat bodies along their flanks. empirical evidence strongly suggests that to the lower areas of river systems, this The channels were rapidly filled with peat accumulated under a humid to per- sediment was pushed out of the channels clastic material, initially clays and silts humid climate and that no empirical sup- with flooding caused by the rising base but ultimately sands, and were flanked port can be adduced for rising sea level level. It was pushed outward over the by mudflats and a network of tidal chan- as the principal driver. In brief, if rising swamp and moved progressively inland nels. We propose that this final portion sea level induces peat formation, modern as the locus of such flooding moved with of channel life history is a reflection not coastlines and coastal shelves around the sea-level rise. only of ice melting and sea-level rise, but the world should be covered by peat also of the coupling of these factors to swamps. These peat-accumulating envi- During this rising phase of sea level, the climate change (e.g., Cecil et al. 2003a, ronments should be advancing ahead channel was converted to an estuary, 2003b; Peyser and Poulsen 2008; Tabor of widespread, now flooded, trailing subject to regular tidal action. This can be areas of time-transgressive blanket peat seen in the nature of the sediments that 7 2 Circular 605 Illinois State Geological Survey constitute the gray-shale wedge, particu- The gray shale onlaps the tree bases, and in the seam along the channel margin, larly in the channel adjacent to the coal in some instances, laminae in the enclos- and clastic wedges up to several feet or peat body and in those parts of the ing sediments can be traced from outside (meters) in thickness and lateral gray-shale wedge that cover the surface of a stump through the shales that filled extents of a few feet (meters) to a few the coal bed. Such sediments bear clear its hollow interior. Stigmarian rooting hundred feet (meters) or so, measured evidence of rhythmicity typical of tidal organs of these trees, identifiable by their orthogonally to the channel axis. The deposits (Archer and Kvale 1993; Archer distinctive external patterns, have been sediment filling these splits is identi- et al. 1995). These sediments vary in char- identified as much as 3.9 in. (10 cm) deep cal to that constituting the roof rock acter, some evidently deposited in mud in the coal bed, filled with roof-shale sed- that lies in gradational contact with flats (Archer et al. 1994; Kvale and Mas- iments, indicating that the hollows in the the top of the coal bed. talerz 1998) and others in tidal channels, standing lycopsid trunks extended down with the rate of deposition varying across into the peat and were filled as muds 3. Detachment of the coal body from the top of the peat locally. Also associated were deposited in and around the tree the seat earth. Adjacent to the chan- with this phase is the development of a bases. In some instances, prostrate lycop- nel are areas where the coal bed is system of tidal channels in areas immedi- sid trunks have been found still attached detached from the seat earth and bent ately adjacent to the main river channel. to standing tree stumps (e.g., DiMichele and stretched or torn. The interval Called “rolls” in mining parlance, these and DeMaris 1987). Prostrate vegeta- between the top of the seat earth features are of limited lateral extent, have tion is abundant, and stems with hollow and the base of the coal is filled with erosional bases and irregular to sinuous central cavities, such as those found in rock identical to the rock that fills the courses, and can contain plant fossils, calamitaleans and lycopsids, are often channel and covers the coal adjacent often differing significantly from those partially to completely filled with the roof to the channel. buried at the top of the coal bed. sediment that encloses them, indicating 4. Sharp contacts occur between peat little or no transport. Models of mud-cast Throughout the area adjacent to the flaps and the underlying gray shales. logs (Gastaldo et al. 1989) demonstrate channel, abundant plant material In areas of suspected floating peat that these develop in place on the surface appears to have been buried rapidly in mats, the basal contacts of the coal of the substrate. Delicate plant parts, place. The sediment surrounding these with the top of the underlying gray such as the stems and foliage of tree plants is the finest of the gray-shale shale are sharp, entirely lacking ferns and pteridosperms, are abundantly wedge, largely claystone to fine siltstone; rooting of any kind, which would be preserved. Moreover, spatial patterns it is very finely laminated but preserves expected were these splits to have of original vegetation are preserved. All evidence of tidal rhythmic deposition. In been splays. Splays are usually recolo-these factors point to rapid burial of the addition, a transitional zone of organic nized by vegetation, and with peat peat surface by flood-borne sediments. shale less than 0.4 in. (<1 cm) to tens of sitting immediately on such splits, inches (centimeters) in thickness often Accompanying conversion of the chan- there absolutely should have been occurs between the top of the normally nel to a tidal estuary, the peat body along rooting from the peat into the shale bright-banded coal and the bottom of the channel margins began to erode and had the peat been deposited after the the gray-shale roof, indicating an early be torn apart, most likely initially along shale. We know of no case, among the flooding stage that was accompanied the fine layers of dark clay partings in the hundreds of exposures of such splits by the onset of death of the vegetation. peat in areas immediately adjacent to the we have observed, where any root- This transitional zone often contains channel. This probably was exacerbated ing occurs. Thus, the gray mudstones abundant fallen stem material, including by the action of daily tides against the appear to have been deposited within large lycopsid trunks that are not sedi- peat margin. In addition, modern studies the splits and not subject to recoloni- ment filled, thus indicating decay in an have shown that flooding of peats leads zation by vegetation after deposition environment where sediment input was to an increase in methane production in of the muds in a flood. low, even if flooding was taking place. the peat body, which can result in flota- 5. Stringers of coal cross gray shales These observations reflect the earliest tion of the peat. In-mine evidence of peat within splits. Dozens of examples phases of gray-shale wedge deposition flotation has been found associated with have been observed wherein thin in areas adjacent to the channel and channels in several different coal bodies stringers of coal pass from the coal show clearly that the gray-shale wedge (Elrick et al. 2008). This evidence includes bench below to the coal bench above was emplaced during the early stages of the following: the gray shale split between such sea-level rise. It is at this stage that we benches. Exhumation of these string- envision the development of extensive 1. Peat or coal “flaps,” in which the ers shows that they are not roots but mud flats along the margin of the chan- detachment of peat leads to an abun- nel, probably colonized by the most dance of flaps along the peat margin generally vitrain sheets or thicker sheets of normally bright-banded flood-resistant vegetation. The most dra- in contact with the channel, varying in coal. This is effectively incontrovert- matic evidence of the rapid early burial thickness from a few inches (centime- ters) to 3.3 ft (1 m) or more. ible evidence that the mudstones of of vegetation is the presence of upright the splits were emplaced following tree bases, nearly always of arborescent 2. Clastic sediment deposited between some kind of disruptive ripping apart lycopsids, extending tens of inches (cen- these peat flaps, leading to the “splits” of the peat body. timeters) to 3.3 ft or more (≥1 m) into the roof shales and rooted in the coal body. Illinois State Geological Survey Circular 605 73 6. Vegetation is in the upright position CONCLUSIONS ACKNOWLEDGMENTS upon tilted peat flaps. Upright, buried stumps of lycopsid trees have been The Galatia channel and similar This study would have been impossible observed above the uppermost peat paleochannels in the Illinois Basin yield without the cooperation of numerous flaps but are tilted so that their verti- valuable insights into patterns of climate mining companies, past and present, who cal axes are orthogonal to the upper and eustasy that controlled Pennsyl- granted us access to their workings and to surface of the coal bed, despite its vanian sedimentation. A dry, seasonal their geologic data. Particularly deserving inclination. These stumps are buried climate at peak interglacial highstand of thanks are the American Coal Com- in the same siltstones and claystones facilitated erosion and sediment trans- pany, Black Panther Mining, Five Star as the roof in areas where the coal lies port from distant source areas. Deltas Mining, Gibson County Coal Company, horizontally and in attachment to its prograded rapidly into the Illinois Basin Peabody Energy, and Sunrise Coal. We seat earth. They indicate that the peat and filled nearly all accommodation thank the National Museum of Natural was floated and distorted during sedi- space. At the onset of a glacial episode, History Small Grants Program for partial ment filling above the peat and injec- the sea level began to fall, exposing the funding of the fieldwork on which this tion into the spaces between floating delta plain. Following a tectonic trough, research is based. flaps. the Galatia river incised a deep valley. Having a low gradient and traversing Tidal deposition continued in the gray- soft sediments, the river meandered REFERENCES shale wedge throughout its thickness actively. Away from the river, calcic Ver- Allgaier, G.J., and M.E. 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Greb and D.R. Chesnut Jr., eds., continent region: Urbana, University of sylvanian black shales: Fieldiana Carboniferous of the Appalachian Illinois, Ph.D. thesis, 100 p. (Field Museum, Chicago), Geological and Black Warrior Basins: Kentucky Memoir 4, 352 p. Geological Survey, Series 12, Special Wright, J.D., R.E. Sheridan, K.G. Miller, Publication 10, p. 71–77. J. Uptegrove, B.S. Cramer, and J.V. 82 Circular 605 Illinois State Geological Survey APPENDIX: TYPE AND REFERENCE SECTIONS OF NAMED UNITS A. Principal Reference Section of the Houchin Creek Coal Member, Carbondale Formation From an unpublished manuscript by Wier (1961, locality 6): Highwall on the north side of an abandoned strip mine, SE NE SW, sec. 3, T3S, R7W, Pike County, Indiana. Map by Wier and Stanley (1953) identifies the site as the Blackfoot Mine. TOP 4.0′ Shale, light to medium gray, thin- to medium-bedded 1.5′ Shale, dark gray to black, slightly calcareous, scattered crinoid columnals and small brachiopods, nodules and thin lenses of gray to tan, finely crystalline limestone 0.9′ Shale, black, fissile 1.2′ Hanover Limestone Member (Stendal Limestone of Wier 1961), black, dense, argillaceous, few fossils (not named), contains lenses of dark gray to tan limestone that is fossiliferous. Unit is lenticular, varies from 0 to 2 ft (0 to 0.6 m) thick. 2.2′ Excello Shale Member, black, fissile, alternating hard and soft layers 0.5′ Houchin Creek Coal Member, bright banded 5.3′ Claystone, light gray, scattered rootlets 4.0′ Shale, light gray, weathers brown, sandy 1.2′ Sandstone, medium gray, silty, calcareous, single bed 28.0′ Sandstone, light gray, fine grained, shaly, mostly thin- to medium-bedded, interlaminated gray sandy shale contains siderite bands. Base under water, close to top of Survant Coal Member, which was mined. Wier and Stanley (1953) reported average Survant Coal thickness of 2.4 ft (0.7 m) at this mine. Total section 48.8 ft (14.9 m). B. Type Section of the Hanover Limestone Member Field notes by S.E. Ekblaw, September 8, 1930: Ravine south of the road east of Hanover School, SW NW SE and NE SW SE, sec. 27, T10N, R11W, Greene County, Illinois. Illinois State Geological Survey, Map Room, open files. TOP 4′± Hanover Limestone Member, brownish to bluish gray, nodular structure with brecciated character, massive, in one or two beds. Abundant blue-gray to black nodules in places. Fossils include crinoids, Composita, Squamularia, fusulinids. 8″ Shale, greenish gray, slightly calcareous 2′± Covered 6″ Clay-shale, bluish gray, noncalcareous 2″ Shale, coaly 2½″ Clay shale, dark bluish gray, noncalcareous, poorly bedded, very slickensided, no fossils 1′6″–2′8″ Houchin Creek Coal Member 1′ Claystone, black, shaly, leafy 2″ Claystone, gray, noncalcareous 2′ Shale, gray, noncalcareous, evenly bedded, fern leaf and stem impressions 83 C. Type Section of the Delafield Member (New) From continuous core of Energy Plus borehole No. ME-13, drilled 2,605 ft (794 m) from south line, 1,274 ft (388 m) from west line, sec. 31, T4S, R6E, Hamilton County, Illinois. Core described by W. John Nelson, January 4–5, 2007. Table A1 Type section of the Delafield Member (new) Thickness (ft) Top depth Bottom depth Rock description 4.6 1,043.7 1,048.3 Springfield Coal Member, bright banded, partly removed by company; depths from company log. 4.7 1,048.3 1,053.0 Top of Delafield Member, claystone (underclay), nearly black at top, changing downward to dark gray, olive gray in lower half. Blocky, thoroughly slickensided, lower 3 ft (0.9 m) calcareous, with scattered small limestone nodules. Lower contact gradational. 6.3 1,053.0 1,059.3 Sandstone, medium gray, very fine grained, micaceous, lithic arenite. Brecciated at the top with zigzag fractures extending downward and irregular masses of dark gray dolomite(?) at top. Dark gray siltstone laminae become more numerous downward, outlining wavy and ripple lamination. Lower contact gradational. 35.7 1,059.3 1,095.0 Sandy siltstone and shale, medium gray, mostly planar laminated, some ripples and horizontal burrows in sand-rich interval, possible tidal rhythmites. Interlaminated light gray sandstone is 10% to 30% of rock, reaching a maximum at 1,068–1,076 ft (325.5 to 328.0 m) and decreasing below that point. Trace fossils Teichichnus and Conostichus identified by J.A. Devera. Lower contact gradational. 22.0 1,095.0 1,117.0 Shale, medium-dark gray, silty, becoming darker and finer downward, laminae of very fine sandstone confined to upper part. “Pyrite trails” common, siderite bands and lenses occur in lower 14 ft (4 m). Lower contact gradational. 6.2 1,117.0 1,123.2 Shale, dark gray, contains little or no silt, very fissile; “pyrite trails” and siderite lenses numerous. Lower contact rapidly gradational, base of Delafield Member. 0.4 1,123.2 1,123.6 Hanover Limestone Member, calcareous shale, grayish black, contains scattered echinoderm and fossil shell fragments; lenses of dark gray, micritic limestone occur near base; lower contact rapidly gradational. 8.4 1,123.6 1,132.0 Excello Shale Member, black, low-density, fissile; phosphatic lenses and pyrite nodules. Concretion of black microgranular dolomite occurs at 1,126.0 to 1,127.7 ft (343.2 to 343.7 m). Lower contact appears erosive; Houchin Creek Coal is absent. 3.0 1,132.0 1,135.0 Sandstone, medium greenish gray, very fine grained, micaceous, lithic arenite. 84 D. Type Section of the Galatia Member (New) Core from Kerr-McGee Corp. borehole No. 7629-16 (sec. 29, T7S, R6E, Saline County, Illinois). This core is in permanent storage at the Samples Library of the Illinois State Geological Survey in Champaign (storage number C-14933). Table A2 Type section of the Galatia Member (new) Thickness (ft) Top depth Bottom depth Rock description 8.7 736.5 745.2 Springfield Coal (core removed by company; depths from other logs). 0.2 745.2 745.4 Coal and shale interlaminated, lower contact sharp and uneven. 3.6 745.4 749.0 Top of Galatia Member, sandstone, light olive gray, very fine grained, argillaceous; root traces throughout, masses of granular siderite near base. Lower contact gradational. 5.0 749.0 754.0 Siltstone, light olive gray, coarse (almost sandstone), moderately fissile, lenses and nodules of siderite common. Lower contact gradational. 8.5 754.0 762.5 Sandstone, medium to light gray, very fine grained, sublitharenite; portions show faint wavy silt and clay laminae, a few siderite lenses. Lower contact gradational. 6.5 762.5 769.0 Siltstone and sandstone, interlayered, lithologies as above. Lamination mostly lenticular and wavy, locally contorted. Rip-up clasts of siltstone in sandstone matrix become more numerous downward. Irregular masses of siderite common. Lower contact gradational. 17.0 769.0 786.0 Sandstone, light gray, very fine to fine grained, litharenite, micaceous. Shale-pebble conglomerate common in upper 11 ft (3.4 m). Plant fossils in siltstone at 770.0–770.9 ft (234.7–235.0 m). Basal 6 ft (1.8 m) is clean, massive sandstone. Lower contact erosional. Base of Galatia Member (thickness 40.6 ft). 2.0 786.0 788.0 Excello Shale Member, black, hard, thinly fissile, phosphatic lenses and laminae; dense dolomite concretion in mid to lower part. 788.0 End of core, total depth. 85 Circular 605, Plate 1 EVOLUTION OF A PEAT-CONTEMPORANEOUS CHANNEL: THE GALATIA CHANNEL, MIDDLE PENNSYLVANIAN, OF THE ILLINOIS BASIN Plate 1: Map of the Southeastern Part of the Illinois Basin Showing the Thickness of the Springeld Coal, Channels That Affect the Coal, and Major Structural Features W. John Nelson, Scott D. Elrick, William A. DiMichele, and Philip R. Ames 2020 Macon Douglas Vermillion Parke >66 inches (168 cm) 42 to 66 inches (107 to 168 cm) Moultrie Edgar 28 to 42 inches (71 to 107 cm) 0 to 28 inches (0 to 71 cm) Christian Coles No coal Insufficient data Vigo Paleochannel Shelby G Anticline S Monocline Clark 1:500,000 0 10 20 mi Cumberland N 0 10 20 km Sullivan Effingham Greene Fayette Jasper Crawford G Lawrence Clay Lawrence Richland Daviess Martin Knox Marion Orange nel Wabash n Wayne ia c ha Edwards t Ga la Pike Dubois Jefferson Crawford Gibson nel ch an a ala ti G Hamilton White PerryWarrick Vanderburgh Posey Spencer Franklin Hancock Breckinridge Gallatin Henderson Saline Williamson | G Daviess |H |G Union Rough Creek Fault System |H | G |H | Union G Grayson Hardin Moo| H rmWaebster | Graysonn S G McLeanH Johnson ync |line |G Ohio Pope |H | G |H | G |H Crittenden Hopkins Pulaski Livingston Muhlenberg Massac ButlerCaldwell Ballard McCracken Warren Lyon ILLINOIS STATE GEOLOGICAL SURVEY © 2020 University of Illinois Board of Trustees. All rights reserved. For Suggested citation: Prairie Research Institute permissions information, contact the Illinois State Geological Survey Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution University of Illinois at Urbana-Champaign of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylva- 615 E. Peabody Drive nian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, Champaign, Illinois 61820-6918 Plate 1 of 6. http://www.isgs.illinois.edu Salem Loud G en G G Mattoon S Clay City GS S SS S S SS Winslow-Henderson channel Sullivan channel G S SS SS GG G ticlinor ium G La Sal le An GG G GG GG GG G G G GG G G ILLINOIS STATE GEOLOGICAL SURVEY EVOLUTION OF A PEAT-CONTEMPORANEOUS CHANNEL: THE GALATIA CHANNEL, Circular 605, Plate 2Prairie Research Institute University of Illinois at Urbana-Champaign 615 E. Peabody Drive Champaign, Illinois 61820-6918 MIDDLE PENNSYLVANIAN, OF THE ILLINOIS BASIN http://www.isgs.illinois.edu Plate 2: Cross Section of the Galatia Channel in the Raleigh Area, Saline County, Illinois W. John Nelson, Scott D. Elrick, William A. DiMichele, and Philip R. Ames N S 2020 <0.26MI> <0.13MI> <0.17MI> <0.13MI> <0.13MI> <0.14MI> <0.12MI> <0.13MI> <0.12MI> <0.13MI> <0.12MI> <0.13MI> <0.35MI> 2171 2172 2165 2163 2177 2178 2207 2206 2200 2198 2197 2199 1521 1523 0 0 Breuer-Robison Oil Co. Breuer-Robison Oil Co. Calvert Drilling, Inc. Calvert Drilling, Inc. Breuer-Robison Oil Co. Breuer-Robison Oil Co. George & Wrather Oil George & Wrather Oil George & Wrather Oil George & Wrather Oil George, T.W. Trust George & Wrather Oil Duncan, Walter Miller, Dee Drlg. Co. Massey, J.H. Massey, J.H. Davis, Ben "A." Davis, Ben "A." Woolard Heirs Woolard Heirs Rhine Rhine Lemons, William H. Lemons, William H. Lemons, William H. Lemons, William H. Blankenship, Walter Stafford, James et al. 10 35-7S-6E 35-7S-6E 35-7S-6E 35-7S-6E 35-7S-6E 35-7S-6E 2-8S-6E 2-8S-6E 2-8S-6E 2-8S-6E 2-8S-6E 2-8S-6E 2-8S-6E 11-8S-6E 50 Spontaneous Spontaneous potential, Resistivity, potential, Resistivity, Spontaneous potential, Resistivity, Spontaneous potential, Resistivity, Spontaneous potential, Resistivity, Spontaneous potential, Resistivity, Spontaneous Resistivity, Spontaneous potential, millivolts Resistivity, Spontaneouspotential, potential, Resistivity, Spontaneous potential, Resistivity, Spontaneouspotential, Resistivity, Spontaneous potential, millivolts Resistivity, Spontaneous Resistivity, ohms, m2/m millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m2/m potential, millivolts millivolts ohms, m 2/m millivolts ohms, m2/m ohms, m 2/m millivolts ohms, m2/m millivolts ohms, m 2/m millivolts ohms, m2/m ohms, m2/m millivolts ohms, m 2/m 20 R6E 100 30 ft m 35 Danville Coal IL Danville Coal Bankston Fork Ls Bankston Fork Ls T7S Brereton Ls T8SBrereton Ls Herrin Coal (datum) Herrin Coal (datum) Galatia channel Briar Hill Coal Briar Hill Coal 2 R5E R6E R7E T7S Springfield Coal Galatia Springfield Coal channel T8S Houchin Creek Coal Saline CountyT9S 11 Houchin Creek Coal Survant Coal T10S Survant Coal lower Survant Coal Colchester Coal Drill hole location map. 1:24,000 0 .5 1 mi N 0 .5 1 km Colchester Coal Circular 605, Plate 2 © 2020 University of Illinois Board of Trustees. All rights reserved. For permissions information, contact the Illinois State Geological Survey Suggested citation: Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, Plate 2 of 6. 0500 0500 ILLINOIS STATE GEOLOGICAL SURVEY Prairie Research Institute EVOLUTION OF A PEAT-CONTEMPORANEOUS CHANNEL: THE GALATIA CHANNEL, University of Illinois at Urbana-Champaign Circular 605, Plate 3 615 E. Peabody Drive Champaign, Illinois 61820-6918 MIDDLE PENNSYLVANIAN, OF THE ILLINOIS BASIN http://www.isgs.illinois.edu Plate 3: Cross Section of the Galatia Channel in Wabash County, Illinois W. John Nelson, Scott D. Elrick, William A. DiMichele, and Philip R. Ames 2020 SW NE <0.18MI> <0.18MI> <0.22MI> <0.24MI> <0.16MI> <0.20MI> <0.18MI> <0.15MI> <0.13MI> <0.13MI> <0.13MI> <0.13MI> <0.13MI> <0.13MI> <0.19MI> 295 2757 1605 28342 1670 4499 4490 1507 1492 1495 4461 1489 1240 1480 446301 183 0 0 Exchange Oil Company George & Wrather Oil Calstar Petroleum Company James R. Cantrell C.E. Skiles, Inc. C.E. Skiles, Inc. C.E. Skiles, Inc. C.E. Skiles, Inc. IL Mid-Continent Company IL Mid-Continent Company Continental Oil Company Continental Oil Company IL Mid-Continent Company IL Mid-Continent Company Tide Water Associated Oil Co. Tide Water Associated Oil Co. Maud A. Strasser No. 1 Lovellette No. 1 Lovellette No. 1 Epler No. D-12 Schrodt No. 1 Schrodt No. 2-A Epler No. D-4 Epler No. D-2 Morris No. 2 Morris No. 1 Seiler No. 8 Seiler No. 5 Grundon No. 1 Grundon No. 3 Seiler No. 3 Seiler No. 2 3-2S-13W 3-2S-13W 3-2S-13W 3-2S-13W 3-2S-13W 3-2S-13W 3-2S-13W 3-2S-13W 35-1S-13W 35-1S-13W 35-1S-13W 35-1S-13W 35-1S-13W 35-1S-13W 35-1S-13W 35-1S-13W 10 50 Spontaneous Spontaneous Spontaneous Spontaneous Spontaneous SpontaneousSpontaneous potential, Resistivity, Spontaneous Spontaneous SpontaneousResistivity, Resistivity, potential, Resistivity, potential, Resistivity, potential, Resistivity, Spontaneous Resistivity, Spontaneous Spontaneous ohms, m2/m potential, Resistivity, Resistivity, potential, Resistivity, potential, Resistivity, potential, Resistivity, potential, Resistivity, Spontaneous Resistivity, potential, ohms, m2/m millivolts millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m 2/m potential, potential potential,millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m 2/m millivolts ohms, m2/m millivolts ohms, m2/m millivolts ohms, m2/m potential,millivolts ohms, m2millivolts /m20 Spontaneouspotential, Resistivity, millivolts ohms, m2/m 100 30 m ft IL 34 35 Danville Coal (datum) Danville Coal (datum) Herrin Coal Herrin Coal marker T1S T2S Briar Hill Coal Briar Hill Coal Springfield Coal 1N13W 1N12W 3 2 Delafield Member Springfield Coal Galatia channel Delafield Member Wabash County marker 1S13W 1S12W Galatia channel Excello Shale Houchin Creek Coal Survant Coal 2S13W 0 .5 1 mi N Houchin Creek Coal 0 .5 1 km lower Survant Coal Drill hole location map. Survant Coal Mecca Quarry Shale Mecca Quarry Shale Suggested citation: Circular 605, Plate 3 © 2020 University of Illinois Board of Trustees. All rights reserved. For permissions information, contact the Illinois State Geological Survey Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, Plate 3 of 6. ILLINOIS STATE GEOLOGICAL SURVEY Prairie Research Institute EVOLUTION OF A PEAT-CONTEMPORANEOUS CHANNEL: THE GALATIA CHANNEL, Circular 605, Plate 4 University of Illinois at Urbana-Champaign 615 E. Peabody Drive Champaign, Illinois 61820-6918 MIDDLE PENNSYLVANIAN, OF THE ILLINOIS BASIN http://www.isgs.illinois.edu Plate 4: Cross Section of the Effingham Channel in the Olney Area, Richland County, Illinois W. John Nelson, Scott D. Elrick, William A. DiMichele, and Philip R. Ames 2020 SW NE <0.64MI> <0.56MI> <0.31MI> <0.47MI> <0.79MI> <0.52MI> <1.02MI> <0.93MI> <0.57MI> <0.56MI> <1.03MI> <0.51MI> 673 647 2897 24208 2831 1710 764 1666 1670 1662 756 672 939 Jack Inglis Oil Prop. Berlin C. Runyon Aimco, Inc. Booth Resources, Inc. Aimco, Inc. Tulley & Carter Co. Calvert Drilling, Inc. Sam Tipps Baines Co. Pruett Sun Drilling Co. Rina & Kinsell Oil C Willard McKinney Morris Runyon No. 2 D. Totten No. 1 D. Totten No. 1 O'Donnell No. 1 Winter No. 1 Hinkel No. 1 Redman No. 1 Benton No. 1 C.E. Harrolle No. 1 J. Herman et al. No. 1 Joe A. Galloway No. 1 Koertge No. 1-B Sutton No. 1 25-3N-9E 25-3N-9E 24-3N-9E 24-3N-9E 19-3N-10E 18-3N-10E 18-3N-10E 8-3N-10E 9-3N-10E 4-3N-10E 4-N-10E 33-4N-10E 33-4N-10E Spontaneous Resistivity, Spontaneous Resistivity, Spontaneous Spontaneous Spontaneous Spontaneous Spontaneous Spontaneous Spontaneous Spontaneous Resistivity, Spontaneous Resistivity,potential, ohms, m2/m potential, potential, Resistivity, Resistivity Resistivity, Resistivity, potential, Resistivity, potential, Resistivity, Resistivity,ohms, m2/m ohms, m2/m potential, Spontaneous potential, potential, 2 2 2 potential, 2 potential, 2 potential, R9E R10E 2 millivolts millivolts millivolts millivolts ohms, m2/m potential, Impedance 2 millivolts ohms, m /m millivolts ohms, m /m millivolts ohms, m /m millivolts ohms, m /m millivolts ohms, m /m millivolts ohms, m /m millivolts ohms, m /m millivolts 2726 25 30 29 28 Olney 35 36 31 32 33 34 IL T4N T3N 1 6 4 2 3Channel margin 5 from Potter (1962) Danville Coal (datum) Danville Coal (datum) 11 12 7 8 9 10 Herrin Coal (base) 14 13 18 17 16 15 Herrin Coal (base) 20 23 24 19 21 22 Briar Hill Coal R9E R10E R14W Springfield Coal Briar Hill Coal 27 26 25 30 29 28 T4N Springfield Coal ? Olney 35 36 31 32 33 34 Delafield Member Coal ? Delafield Member T3N Drill hole location map. 0 1 mi N 0 1 km T2N Houchin Creek Coal Richland CountyHouchin Creek Coal Sandstone Survant Coal Survant Coal Colchester Coal Colchester Coal Circular 605, Plate 4 © 2020 University of Illinois Board of Trustees. All rights reserved. For permissions information, contact the Illinois State Geological Survey Suggested citation: Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, Plate 4 of 6. ILLINOIS STATE GEOLOGICAL SURVEY EVOLUTION OF A PEAT-CONTEMPORANEOUS CHANNEL: THE GALATIA CHANNEL, Circular 605, Plate 5Prairie Research Institute University of Illinois at Urbana-Champaign 615 E. Peabody Drive Champaign, Illinois 61820-6918 MIDDLE PENNSYLVANIAN, OF THE ILLINOIS BASIN http://www.isgs.illinois.edu Plate 5: Cross Section of the Effingham Channel in the Stewardson Area, Shelby and Effingham Counties, Illinois W. John Nelson, Scott D. Elrick, William A. DiMichele, and Philip R. Ames 2020 N Shelby County Effingham County S <0.90MI> <1.52MI> <0.53MI> <1.63MI> <0.95MI> <0.31MI> <1.67MI> <1.79MI> <0.98MI> <0.71MI> <2.03MI> <2.05MI> <0.90MI> <3.79MI> <4.81MI> <1.23MI> 24363 24342 24366 22918 431 24385 1288 23118 452 1086 24220 1113 24850 530 24202 25131 25023 Mathis-Stremming Comm. No. 1 Stremming No. 1 Manhart No. 1 Vail No. 1 Scheef Heirs No. 1 Tomkins et al. No. 2 Rincker No. 2 Probst No. 1-A Moomaw, Wm. No. 1 Trueblood, Irven No. 1 Culver No. 1 Kaufman No. 1 Kelly No. 1 Seeley, L. No. 1 Fink No. 1-17 Pike No. 1 Anita Lake Comm. No. 1 R. K. Petroleum Corp. R. K. Petroleum Corp. R. K. Petroleum Corp. Jordan Oil & Gas Co. Bergundthal, E. J. Pinnacle Exploration Corp. Brown, Ray et al. Nuxoll, William R. Luttrell, Homer et al. Schaefer, James L. R K Petroleum Corp. Ward Marion F. MDM Energy, Inc. Steinlage Arnold F. Dart Energy Corp. MDM Energy, Inc. MDM Energy, Inc. 0 0 4-10N-5E 5-10N-5E 17-10N-5E 17-10N-5E 21-10N-5E 22-10N-5E 22-10N-5E 28-10N-5E 34-10N-5E 4-9N-5E 4-9N-5E 15-9N-5E 27-9N-5E 35-9N-5E 17-8N-5E 25-8N-5E 26-8N-5E GR – density/neutron GR – density/neutron GR – density/neutron GR – density/neutron Electric (1993) GR – density/neutron Electric (1961) GR – induction Electric (1950) Electric (1957) GR – density/neutron Electric (1957) GR – sonic Electric (1946) GR – induction GR – density/neutron GR – induction Self potential, Resistivity, Resistivity, Spontaneous potential, Resistivity,10 millivolts ohms, m2/m ohms, m2/m ohms, m2/m Self potential, Resistivity, 20 21 22 23 24Self potential, Resistivity, millivolts 2 19 20 21 22 23 24 19 20 21 22 23 24 19millivolts ohms, m /m millivolts ohms, m2/m 50 29 28 27 26 25 30 29 28 27 26 25 30 29 28 27 26 25 30 32 33 34 35 36 20 31 32 33 34 35 36 31 32 33 34 35 36 31 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 6 IL 8 9 10 11 12 7 8 9 10 11 12 7 8 9 10 11 12 7 100 30 m ft 17 16 15 14 13 18 17 16 15 14 13 18 17 16 15 14 13 1810N 4E 10N 5E 10N 6E 20 21 22 23 24 19 20 21 22 23 24 19 20 21 22 23 24 19 29 28 27 26 25 30 29 28 27 26 25 30 29 28 27 26 25 30 Danville Coal 32 33 34 35 36 31 32 33 34 35 36 31 32 33 34 35 36 31 Danville Coal 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 6 Anna Shale/Herrin Coal 8 9 10 11 12 7 8 9 10 11 12 7 8 9 10 11 12 7 Herrin Coal 17 Shelby16 15 14 13 18 17 16 15 14 13 18 17 16 15 14 13 18 Springfield Coal Turner Mine Shale/ 9N 4E 9N 5ER1E R2E R3E R4E R5E R6E R7E 20 21 22 23 24 9N 6E19 20 21 22 23 24 19 20 21 22 23 24 19 Springfield Coal EffinghamT14N 29 28 27 26 25 30 29 28 27 26 25 30 29 28 27 26 25 30 Moultrie 32 33 34 35 36 31 32 33 34 35 36 31 32 33 34 35 36 Effingham Effingham 31 T13N 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 6 channel channel Delafield Member 8 9 10 11 12 7 8 9 10 11 12 7 8 9 10 11 12 7 T12N 17 16 15 14 13 18 17 16 15 14 13 18 17 15 14 13 18 base of Excello Shale 16base of Excello 8N 4E 8N 5E 8N 6E (datum) Shale (datum) T11N Shelby 20 21 22 23 24 19 20 21 22 23 24 19 20 21 22 23 24 19 upper Survant Coal 29 28 27 26 25 30 29 28 27 26 25 30 29 28 27 26 25 30 T10N Survant Coal 32 33 34 35 36 31 32 33 34 35 36 31 32 33 34 35 36 31 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 6 lower Survant Coal T9N 5 4 Mecca Quarry Shale incised valley from base of Houchin Creek Coal T8N Drill hole location map. 0 3 mi Mecca Quarry Shale N 0 4 km T7N Fayette Effingham Mecca Quarry Shale/ T6N Colchester Coal Circular 605, Plate 5 © 2020 University of Illinois Board of Trustees. All rights reserved. For permissions information, contact the Illinois State Geological Survey Suggested citation: Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, Plate 5 of 6. ILLINOIS STATE GEOLOGICAL SURVEY Prairie Research Institute EVOLUTION OF A PEAT-CONTEMPORANEOUS CHANNEL: THE GALATIA CHANNEL, Circular 605, Plate 6 University of Illinois at Urbana-Champaign 615 E. Peabody Drive Champaign, Illinois 61820-6918 MIDDLE PENNSYLVANIAN, OF THE ILLINOIS BASIN http://www.isgs.illinois.edu Plate 6: Cross Section of the Leslie Cemetery Channel, Warrick and Gibson Counties, Indiana W. John Nelson, Scott D. Elrick, William A. DiMichele, and Philip R. Ames 30 29 28 27 26 25 2020 31 32 33 34 35 36 Gibson County 3S 9W SW Warrick County Gibson County NE Warrick County 4S 9W 6 5 4 3 2 1 < 0 .6 5 MI > <0.17 MI> <1.15 MI> < 0 .68MI > < 0 .51MI > < 0 .28MI > < 0 .28MI > < 0 .79MI > <0.46 MI> <0.29 MI> < 0 .52MI > < 0 .64MI > < 0 .67MI > 7 8 9 10 11 12 156042 117030 10022C 156033 117002 117001 116996 116995 117032 957 152501 132972 132973 152504 IN 0 0 Johnson et al. Unit No. 1 Yeck No. 1 Sumner No. 1 Peabody Coal Co. No. 8 Scholl No. 1 Adam Splittorff No. 1 Rentchler No. 1 Renchler "A" Lse No. 1 Grimm et al. No. 1-Comm. Zint No. 1 Rice & Tyrus et al. No. CU-1 Kroeger No. 1 Scholz No. 1 Bittner No. 1Beerbower National Associated Petroleum Co. Hercules Petroleum Co. Eastern Natural Gas Corp. Reznik R.K. Petroleum R K Petroleum Corp. RK Petroleum T & H Corp. Wheeler Oil Inc. Wheeler Oil Inc. RK Petroleum Bury Howard Energy Corp. 18 17 16 15 14 13 Spontaneous Spontaneous Resistivity, Spontaneous potential, Conductivity,Spontaneous SpontaneousSpontaneous potential, Spontaneous Resistivity, Resistivity, potential, Resistivity,2 potential, millivolts millimhos potential, Spontaneous10 Resistivity, ohms, m /m potential, ohms, m2/m millivolts potential, Resistivity,potential, millivolts ohms, m2/m ohms, m2/m millivolts ohms, m2/m Spontaneous2 Resistivity, millivolts ohms, m /m millivolts millivolts millivolts potential, 2 50 Resistivity, Induction Resistivity millivolts ohms, m /m 19 20 21 22 23 24 –ohms, m2/m Gamma Danville Coal Ray 20 30 29 28 27 26 25 100 30 m ft 31 32 33 34 35 36 Winslow channel Folsomville Member St. David Limestone Turner Mine Shale Drill hole location map. 0 1 mi Springfield Coal Turner Mine Shale N1S 11W 1S 10W Springfield Coal 0 1 km TD = 207.28 2S 12W 2S 11W 2S 10W 2S 9W Delafield Member Delafield Gibson County Member 3S 13W 3S 12W 3S 11W 3S 10W 3S 9 W Galatia Member (Francisco channel) 4S 11W 4S 10 W 4S 9W 4S 8W 4S 7W 4S 6W Hanover Limestone Hanover Limestone Excello Shale (Datum) Excello Shale (Datum) Houchin Creek Coal Houchin Creek Coal 5S 9W 5S 8W 5S 7W Survant Coal Warrick County TD = 276 6S 9W 6S 8W Survant Coal 7S 8W Circular 605, Plate 6 © 2020 University of Illinois Board of Trustees. All rights reserved. For permissions information, contact the Illinois State Geological Survey Suggested citation: Nelson, W.J., S.D. Elrick, W.A. DiMichele, and P.R. Ames, 2020, Evolution of a peat-contemporaneous channel: The Galatia channel, Middle Pennsylvanian, of the Illinois Basin: Illinois State Geological Survey, Circular 605, Plate 6 of 6. nnel ha mete ry c e Ce Lesli