SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES • NUMBER 11

Underwater Television Survey of the Atlantic Outer Continental Margin near Wilmington Canyon

Daniel J. Stanley and Peter Fenner

ABSTRACT

Stanley, Daniel J., and Peter Fenner. Underwater Television Survey of the Atlantic Outer Continental Margin near Wilmington Canyon. Smithsonian Contributions to the Earth Sciences, number 11, 54 pages, 18 figures, 1973.—The study summarizes the results of an underwater television survey of the sea floor at the shelfbreak and at the head of Wilmington Canyon off the Middle Atlantic States. Distributions are shown for bottom currents and sedimentary structures, suspended matter, bottom firmness, bottom lithology, shell percentage, and fauna. A number of man-made objects on the sea floor in this area is documented. The Appendix is a listing of observations made at 26 stations. These data, based on direct visual observation of the sea floor, serve to complement earlier marine geological investigations made in this region. Mapping shows that surficial outer shelf and canyon head sediments at the shelfbreak are undergoing modification by both bottom current processes and bioturbation and that at the present time the Wilmington Canyon is receiving sediment mainly from the adjacent margin. Gravel, oyster banks, and near-vertical cavernous cliffs occurring at depths between 100 and 200 m are relict features related to eustatic changes of sea level that affected the outer continental margin during the Pleistocene.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution’s annual report, Smithsonian Year. SI PRESS NUMBER 4785. SERIES COVER DESIGN: Aerial view of Ulawun Volcano, New Britain.

Library of Congress Cataloging in Publication Data

Stanley, Daniel J.

Underwater television survey of the Atlantic outer continental margin near Wilmington Canyon.

(Smithsonian contributions to the earth sciences, no. 11)

1. Continental margins—United States. 2. Television in oceanography. I. Fenner, Peter, 1937— joint author. II. Title. III. Series: Smithsonian Institution. Smithsonian contributions to the earth sciences, no. 11.

QE1.S227 no. 11 [GC84.2.U5] 550′.8s [551.4′614′6] 72–13421

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 65 cents (paper cover)

Contents

Introduction

Area of Study

Methods and Techniques

Suspended Matter and Bottom Currents

Firmness of the Sea Floor

Major Lithological Types

Shell Fraction in Surficial Sediments

Fauna and Bioturbation

Man-made Objects

Conclusions

Literature Cited

Appendix

Underwater Television Survey of the Atlantic Outer Continental Margin near Wilmington Canyon

Daniel J. Stanley and Peter Fenner

Daniel J. Stanley, Division of Sedimentology, Smithsonian Institution, Washington, D. C. 20560. Peter Fenner, Governors State University, Park Forest South, Illinois 60466.

Introduction

This publication represents an effort to make available in one place all of the source data obtained during an underwater television survey as one of a series of investigations concerned with sedimentation patterns on the outermost reaches of the broad continental shelf bordering the Middle Atlantic States. Direct visual observations relating to bottom sediment types and the distribution of faunal elements are presented here for the first time.

The present series of investigations includes a morphologic and subbottom reconnaissance (Kelling and Stanley, 1970), a photographic and bottom-sampling program (Stanley and Kelling, 1968), and water-mass configuration and movement studies (Fenner et al., 1971; Lyall et al., 1971). Direct observation of bottom neocurrent activity, water-mass movement, and sediment transport was made by underwater television and was in part reported on elsewhere (Stanley et al., 1972). This, a relatively novel observational technique, has been used with success in other areas (Stamp, 1953; Eddy et al., 1967; Drapeau, 1970).

The specific area we examined by the underwater television technique is about 175 km southeast of Delaware Bay, at the head of Wilmington Canyon and at the break between the outermost continental shelf and upper continental slope (Figure 1). It was selected in accordance with the overall plan for this series, in which successive cruise itineraries were conditioned by the results of previous determinations, e.g., of bathymetry, structure and strati-graphic setting, water mass, and bottom type and aspect.

Sedimentation in canyons heading in deep water far from land remains enigmatic. Our studies have led us to infer that the head of the Wilmington Canyon has, both now and in the recent geologic past, trapped sediment moving on the outer shelf. The hypothesis that sediment is being funneled downslope through the Canyon was assessed in a previous paper (Stanley and Kelling, 1968).

Data presented herein were gathered during a cruise (RoS₄) made aboard the USCGC Rockaway (WAGO377) from 11 to 18 July 1968.

ACKNOWLEDGMENTS.—We thank the U.S. Coast Guard Oceanographic Unit for ship time and the captain, officers, and men of the USCGC Rockaway for their help in carrying out the work at sea. Dr. G. Kelling, University of Wales, helped in the planning phases of this cruise as well as in the collection of data. We were also aided by Dr. D. J. P. Swift, Marine Geology and Geophysical Laboratory, National Oceanographic and Atmospheric Administration, Mr. J. A. Good, Hydro Products, and Messrs. G. Bloomer, D. Eby, E. Gruenstein, and D. Kersey. Messrs. H. Sheng and

FIGURE 1.—Television stations occupied in and near the head of Wilmington Canyon east of the Middle Atlantic States in July 1968. Data collected along the station tracks are shown in Appendix. Depth in this and other charts given in fathoms (1 fathom = 1.83 m).

L. B. Isham, Smithsonian Institution, helped with drafting. Dr. G. Kelling and Dr. H. D. Palmer, Westinghouse Ocean Research Laboratory, criticized the manuscript. We alone take responsibility for errors that may remain. Financial support was provided by Smithsonian Research Foundation grant nos. 233770 and 234230 (D. J. S.) and Governors State University (P. F.).

Area of Study

Details of the physiography and topography of the area studied are given by Kelling and Stanley (1970). Figure 1 shows the ship’s track at the 26 television stations occupied during a period of very low wind and fairly calm seas. Bottom control, necessary to keep to a planned track, was based on bathymetric records and PESR (Precision Echo Sounding Recorder) records taken continuously throughout the cruise.

Methods and Techniques

Video monitoring and recording equipment were continuously manned during all times when the underwater television rig was submerged (at depths to 426 m). The system included a light source, suspended penetrometer, and vaned compass attached to the frame on which the camera was mounted (Figure 2). The compass (diameter, 7.5 cm) serves as scale.

Greenwich Mean Time was used as the basic reference for all notations and recordings of continuously monitored data—bathymetry and bottom-viewing—and for regularly made observations—navigational fixes, course changes, weather observations, and hourly expendable bathythermograph, surface-water temperature, and salinity records.

In addition to written notes, the videotape recorder was used to record a running commentary of sightings, data collected, and speculations on explanations of observations. The audio track of

FIGURE 2.—Photographs on deck of USCGC Rockaway showing underwater rig used on cruise RoS₄: A, television gear, mounted in a steel frame (120 cm × 120 cm × 120 cm), and large stabilizing vane was lowered off the stern and kept just above the sea floor as the ship drifted; B, camera (a) [Hydro Products Model TC 100], 1000-watt mercury vapor light (b) mounted in cage and attached to 460 m long cable. Compass (c) was suspended far enough from frame to be free from the effects of its magnetic field. Tapered and scaled shaft (penetrometer, d) was hung below all other equipment so as to be in view when striking sea floor.

FIGURE 3.—Features such as oriented polychaete tubes (Station 19, 346 m), on upper slope west of the Canyon, provide information on botton currents. In this sequence, note the realignment of tube (in rectangle) resulting from turbulence caused by the cage motion above the sea floor.

the videotapes was later found to be extremely helpful in reconstructing observations and organizing conclusions.

Details on light and camera angles, technical data on instruments used, and operating conditions for the gear are given elsewhere (Stanley et al., 1972). The photographs in the plates of the present paper are, for the most part, reproductions of images stored on one tape, transferred to another, kinescoped, photographed, then enlarged and made into new negatives with prints for use here. These fifth generation reproductions have suffered much in the process.

Data concerning most variables, save navigational specification (see Figure 1, for all locations), are

FIGURE 4.—Sequence of photographs made from video tapes shows turbulence initiated as compass strikes muddy bottom (A) (Station 18, 134 m). After a few seconds (B) mud brought into suspension is slowed by SSE moving current and then (C) the cloud begins movement to the S and SSW (about 10 cm/sec) and out of view. Compass diameter, 7.5 cm.

FIGURE 5.—Chart showing evidence of neocurrent activity in and near the head of Wilmington Canyon (from Stanley et al., 1972). Arrows depict direct observation of sediment movement of currents above the bottom (based on sediment movement or heeling over of sessile fauna). Indirect evidence of recent current activity (based on alignment of ripple mark crests, polychaete tubes and aligned shells) is also depicted.

listed in the Appendix. Summarized are raw observational and interpretative data such as: station number and physiographic location; date and time; depth; inferred bottom-sediment texture; resistance to penetration (firmness); the nature, orientation, and dimension of ripple marks and other features indicating current movement, including oriented organic structures; velocity of suspended sediment movement along the bottom; nature and distribution of shell fragments; and the relative amounts of materials suspended in the water near the bottom.

A partly edited, untitled version of a short film, and the more than 20 hours of videotapes from which it was made, are available from the Sedimentology Laboratory, National Museum of Natural History.

Suspended Matter and Bottom Currents

Suspended matter and current activity were observed everywhere throughout the area of study—on the outermost continental shelf, shelfbreak, canyon head proper, and upper slope—but not uniformly developed. Ripple marks, aligned polychaete tubes (Figure 3), and shells were used to infer current directions, and particles streaming along the sea floor past a fixed object of known size provided a means for measuring bottom-current velocities (Figure 4). Data included in the Appendix are fully discussed in Stanley et al. (1972).

In sum, current activity ranged from barely detectable to about 20 cm/sec and did not follow a uniform pattern (Figure 5). There is, however, a net southerly and downslope orientation to current flow within the Canyon. Medium to large concentrations of suspended matter just above the sea floor (Figure 6) help explain the generally poor clarity of photographs made in earlier surveys of this area (Stanley and Kelling, 1968). Figure 6 depicts a rather subjective classification of concentrations of suspended matter, and shows that higher concentrations most often occur higher on the shelf side of the shelfbreak. There is also a suggestion of a slight westward offset of the medium-clarity water from the Canyon axis, particularly in the headward part, which may reflect large scale motion of shelf and slope water in this region during the period of the survey.

FIGURE 6.—Chart showing distribution of layer of suspension-rich water above the sea floor as observed by television. During the period of the cruise (11 to 18 July 1968) somewhat higher concentrations of suspended sediment were noted in the area landward of the shelfbreak than in the Canyon head proper. A slight westward offset away from the Canyon is also observed.

Firmness of the Sea Floor

Penetration into the sea floor of a scaled stainless steel shaft (see penetrometer in Figure 2Bd) provides a relative scale of bottom firmness. Areas of deep (> 24 cm), medium (15–24 cm), and shallow penetration (< 15 cm) were thus designated and mapped (Figure 7).

Data summarized in the Appendix show that most of the sea floor of the outer shelf and uppermost slope regions not near the Canyon is characterized by low to very low penetration. This firm surface is indicative of a shelly, gravelly sand cover. A zone of medium penetration occurs at the very head of the Canyon and along much of its eastern wall to a depth of about 200 to 450 m and appears to be indicative of sandy mud, silt, clay, or mixtures of these grades. The least firm sedimerits

FIGURE 7.—Chart indicating bottom firmness, based on amount of penetration of scaled shaft into the surficial sediment. Generally firmer sediment on the east canyon wall reflects the presence of coarser sediment tongues draping on that wall as opposed to the west wall.

occur in the Canyon proper and a distributary canyon cut into the shelf west of the head and reflect a soft clay or ooze bottom (Figure 8). On the western margin, the contact between firm and soft surfaces is more abrupt, and tends to occur at a shallower depth than on the eastern wall, appearing near the shelfbreak.

Organic mounds and tracks, ripple marks, other primary sedimentary structures, and the nature of the sediment cloud produced by instruments hitting the sea floor, all aided in further interpretation of the bottom firmness.

These techniques help to define the generally abrupt “mud line,” a boundary, despite tradition, not strictly parallel to the shelfbreak.

Major Lithological Types

The contoured regional distribution of major surficial sediment textural types is shown in Figure 9.

FIGURE 8.—Sequence showing deep penetration (at least 24 cm) of scaled shaft in soft sediment on the west wall of the canyon head (Station 16A, 256 m).

The categories shown are: (a) rock ledges (Figure 10) and bedrock obviously discernible directly from the videotapes, and large broken rock talus (Figure 11); (b) admixtures of pebbles, shell and

FIGURE 9.—Chart showing distribution of major lithological types in the study area. Note presence of rock outcrops in the canyon head near the shelfbreak, and the draping of sand and gravel on the east wall well into the canyon. The “mud-line” is not strictly parallel to the shelfbreak indicating that spill-over and off-shelf processes have been active in recent time.

FIGURE 10.—Sequence showing cavernous rock outcrop just below the shelfbreak on the west wall of the Canyon (Station 16, 120–130 m). This unit forms low “cliffs” with a relief of 5 to 10 m, and is populated by numerous fish and occasional lobsters. The rock is poorly consolidated at the surface as indicated by breaking of outcrop by the penetrometer.

coarse sand (also directly discernible from tape), locally including finer sediment (Figure 12); (c) admixtures of medium to fine sand and sandy silt, generally indicated by degree of penetration of the penetrometer, and the presence of associated features such as ripple marks amply illustrated in Stanley and Kelling (1968; and also detected by direct observation when cage is at rest on sea floor); and (d) mud, including silty and stiff clay, as judged by appearance on the monitor, amount of penetration, and as indicated by the character of the mark made on the bottom or the nature of the sediment cloud raised by the cage and suspended instruments (Figure 8).

Categories b and c generally include shelly sands. The character of sedimentary structures and organic tracks, burrows and mounds (“lebensspuren”) provide additional evidence of the nature of bottom sediment type.

Views of rock outcrops along the canyon walls provide some of the more spectacular footage of the television tapes. The most obvious outcrops of bedrock occur on the west side of the canyon wall. There, large clifflike protruding edges of some exposures of cavernous rock occur at depths ranging from 110 to 135 m (Figure 10). Locally, the exposures are sufficiently friable to be easily broken by the weight of the penetrometer. On the eastern side of the canyon, rock exposures were found to be different in character; they form isolated patches with numerous flat-lying surfaces frequently burrowed but not particularly cavernous. Texture of the bedrock appears to be medium to fine. The patchy occurrence of outcrops shown in Figure 9 is in part an artifact resulting from the sample net and subsequent plotting. Furthermore, in the areas west of the canyon where we found outcrops, they tended to be continuous, running perhaps for hundreds of meters; on the eastern side, however, the outcrops occur as smaller patches (< 1000 m²) throughout the area where they are plotted. The paired nature of outcroppings across the canyon is also, in part, an artifact resulting from the sample grid.

The coarser surficial sediment consisting of gravel and coarse sand (areas of very low penetration) was found covering much of the outermost shelf area in the vicinity of the canyon, in waters generally less than 180 m deep; however, these

FIGURE 11.—Rock outcrops of the type shown in Figure 10 fail (“rock fall”), thus producing boulders and cobbles encountered at deeper depths in the Canyon and on the upper slope. Here a sequence of photographs (Station 12, 278 m) show a large (> 1 m diameter) shell-encrusted block resting on mud. Note fish on rock (B).

FIGURE 12.—Concentrations of large pelecypod valves including oysters (A) and gravel on the upper slope just west of the Canyon (Station 19, 196 m). These patches of anomalous sediment types are relict deposits probably related to eustatic lower stands of sea level.

coarser grade sediments tend to drape into deeper water along the eastern canyon wall. Pebbles and cobbles were observed to depths of at least 320 m at Station 8.

Medium to finer grade sand and sandy silt tend to cover the upper margins of the canyon proper and are, in fact, the predominant textural types serving as the upper canyon head fill. This lithological type is also the predominant facies in those areas of the shelf not covered by gravel and coarse sand.

The predominantly muddy facies are located axially and extend shelfward to depths of about 90 m at the very northward sector of the canyon head. Similarly, mud can be found in tributary canyons entering the canyon proper. The “mud line” cannot be well defined on the west canyon wall because television stations generally did not extend to the same depths as on the east wall (i.e., drift of the ship prevented the television cage from hanging vertically).

The sediment textural distribution confirms earlier conclusions based on bottom photography (Stanley and Kelling, 1968), subbottorn (Kelling and Stanley, 1970) and current studies (Fenner et al., 1971), and more generalized data that sand spill-over from the outer shelf into the Canyon has continued until recent time and may still be an active process at present. As a result, sand is a predominant fraction in certain parts of the canyon head.

Shell Fraction in Surficial Sediments

Shell is one of the predominant components of surficial sandy sediment on the continental shelf. This fraction, mostly whole or fragmented disarticulated pelecypod valves, accounts for more than 30 percent of the total sediment. Shell content tends to vary inversely with depth, the decrease of shell amount coinciding roughly with the break in slope. On the eastern canyon margin, however, the distribution of shell-rich sediment coincides with that of the sand-rich sediment, draping from the shelf edge into deeper water.

A scale of relative shell abundance was devised (Figure 13). Outermost shelf sediment was found generally to contain more than 25 percent shell, while patches of shell-deficient sediment occur on the shelf in the vicinity of gravel and coarse sand patches.

Local concentrations of large pelecypods and gravel occur between about 130 and 200 m (Figure 12). It is possible that certain of these may be remnant oyster banks of the type found in other sectors of the Atlantic shelf at lesser depths (Merrill et al., 1965; Emery, 1968) and dating from low stands of sea level during the Pleistocene Epoch.

Fauna and Bioturbation

Living fauna is a common element in all videotapes, and the organic forms observed have been grouped into four generalized categories and their distribution is summarized on Figure 14: (a) non-shelled swimming forms, mostly fish (Figures 10; 15C, D; 17C) and, locally, squid (Figure 16); (b) shelled bottom dwellers, e.g., pelecypods (Figure 12),

FIGURE 13.—Chart showing distribution of shell (including whole and fragmental matter), in surficial sediment. Note rapid decrease in shell percentage in water depths below shelfbreak.

FIGURE 14.—Distribution of major benthic organisms as observed with television. Note sharp faunal breaks between the outer shelf and the Canyon head.

FIGURE 15.—Organisms in the water mass above the sea floor: A, concentration of planktonic forms at northern end of Canyon head (Station 7, 238 m); B, shrimp on east wall of Canyon (Station 11A, 302 m) ; C, D, school of small fish on the upper slope west of Canyon (Station 19, 347 m).

bryozoans, and echinoderms; (c) soft-bodied bottom dwellers, e.g., sea pens (Figure 17A), co-elenterates (Figure 17B), and worms; (d) crustaceans, including mainly crabs (Figure 17D), shrimps (Figure 15B), lobsters, and sea spiders.

The nonshelled swimming forms are most common just within the Canyon proper, and especially on the west margin of the Canyon. Localized concentrations of fish and plankton (Figure 15A) are also noted on the shelf north of the canyon reentry. Like the fish themselves, fish “nests” are concentrated in fine-grained sediment below the shelfbreak. As detailed in the previous section, pelecypod and related fragments dominate the surficial shelf sediments and decrease notably beyond the shelfbreak. The distribution of echinoderms is generally irregular and patchy, but locally single faunal types predominate (see Appendix).

Crustaceans are more commonly observed below the shelfbreak, the larger forms (i.e., lobsters) frequently concentrating in or near the cavernous rock outcrops where benthic fish are also abundant.

Sea pens and coelenterates are limited depth-wise below the shelfbreak and, together with worms, are most abundant in finer grained sediment within the Canyon. They locally dominate

FIGURE 16.—Sequence showing squid moving past television cage and releasing ink, in the head of Canyon (Station 6, 148 m).

the faunal assemblage along the west margin of the Canyon. One area distinguished by this assemblage was also observed just northeast of the very head of the Canyon. The concentration of worm burrows increases canyonward beyond the shelfbreak (Stanley, 1971a). These burrowing organisms not only modify the strength of sediment, but also contribute to the addition of suspended sediment in the water mass (worms were seen ejecting small clouds of mud as the cage moved slowly above the bottom). Fish also were seen stirring the bottom, and they are important in modifying the sea floor and contribute in a small way to the sediment in suspension (Stanley, 1971b).

Man-made Objects

Human artifacts constitute minor but, in our opinion, significant components of the sea floor in the study area which lies below the east coast shipping lane. Considering our very limited field of view, even the dozen or so whole, large, objects observed during a 5-day period suggest that there is a growing amount of material accumulating even at this distance from shore.

Observations of such materials included bottles (Stations 5, 12), cans (Station 3A), paper (Station 19; Figure 18), and a large polelike object. Materials of smaller size were not recorded, and in most cases would have been very difficult to observe due to the camera’s motion through the water. The high percentage of artificial fibers filtered from water samples collected in this area on a subsequent cruise (Lyall et al., 1971) attests to the importance of man-introduced materials on this sector of the outer continental margin.

Fenner et al. (1971) have shown that this region is one of significant bottom-current activity, hence we can speculate that only a short period of time has elapsed since the objects observed were deposited. The origin of one bottle with a distinct shape was identified, though not recorded on videotape (this type of bottle had been commercially

FIGURE 17.—Example of benthic organisms in the study area: A, large worm tubes extruding from the sea floor on east wall of Canyon (Station 8, 320 m) ; B, anemones on uppermost slope east of Canyon (Station 12, 312 m) ; C, benthic fish (outlined) extending out of large mud depression on west wall of Canyon (Station 13, 267 m) ; and D, crab moving past penetrometer on upper slope east of Canyon (Station 12, 311 m).

introduced only a half-year or so before the cruise). Considerably more man-made objects are presumably buried in the sediment.

Conclusions

Examination of the sea floor and mapping of the outer Atlantic margin near the head of Wilmington Canyon with underwater television supplements observations made in earlier surveys of this region. Among features of particular interest are:

(1) the apparent intensity of bottom-current activity and the abundance of suspended matter above the sea floor in the depth range from G5 to 430 m, even though the survey was made in very calm weather and low sea state; (2) the abundance of benthic organisms and intensity of reworking (bioturbation) throughout the study area; (3) the draping of sandy sediment tongues on the east wall into the Canyon axis, and the shallower position of the “mud line” near the shelfbreak on the west Canyon wall; (4) the exposure of cavernous rocky cliffs on the west wall concentrated between 110 and 135 m depth; (5) the concentration of pelecypods,

FIGURE 18.—Sequence (A–C) of videotape showing compass catching long paper on the upper slope west of Canyon (Station 19, 200 m).

including oysters, and gravel in pockets between 130 and 200 m; and (6) the significant number of large man-made objects even in this area located far from land.

The first three observations listed above indicate that surficial sediments, including sand, are being actively moved by the water mass and continuously reworked by organisms. This current activity results in a net downslope transport from the shelf edge onto the upper slope and into the Wilmington Canyon proper. Spill-over from the shelf onto the east Canyon wall is prevalent. Organisms apparently accelerate this off-shelf process by modifying the physical properties of the sediment wedge.

The submerged cliffs, gravels, and oyster banks are relict features resulting from events related to eustatic lowering of sea level in Pleistocene time. The cliffs are at depths that suggest that they were subaerially exposed river- and ocean-cut bluffs. The gravels, undoubtedly of river origin, help pinpoint the position of fluvial deposits and coarse deltaic concentrations formed at the shelfbreak by major rivers that drained the northeastern United States and traversed the subaerially exposed continental shelf during the Pleistocene. The localized oyster “patches” and other pelecypod concentrations were also formed when sea level was considerably lower (at least about 120 m lower), in Wisconsin time.

The presence of man-made objects on the sea floor below shipping lanes is not in itself surprising. It does serve to emphasize, however, the importance of this type of refuse as an important element of surficial sediments and one likely to increase unless dumping from ships is more tightly controlled.

Underwater television has proved a valuable tool, and its use by marine scientists who plan reconnaissance mapping and regional surveys is advocated. Nothing can surpass this direct visual examination of the ocean floor.

Literature Cited

Drapeau, G.

1970. Sand Waves on Browns Bank Observed from the Shelf Diver. Maritime Sediments, 6:90–101.

Eddy, J. E., V. J. Henry, J. Hoyt, and E. Bradley

1967. Description and Use of an Underwater Television System on the Atlantic Continental Shelf. U. S.Geological Survey Professional Paper, 575–C:C72–C76.

Emery, K. O.

1968. Positions of Empty Pelecypod Valves on the Continental Shelf. Journal of Sedimentary Petrology, 4:1264–1269.

Fenner, P., G. Kelling, and D. J. Stanley

1971. Bottom Currents in Wilmington Submarine Canyon. Nature, Physical Sciences, 229:52–54.

Kelling, G., and D. J. Stanley

1970. Morphology and Structure of Wilmington and Baltimore Submarine Canyons, Eastern United States. Journal of Geology, 78:637–660.

Lyall, A., D. J. Stanley, H. N. Giles, and A. Fisher, Jr.

1971. Suspended Sediment and Transport at the Shelf-break and on the Slope. Marine Technology Society Journal, 5:15–27.

Merrill, A. S., K. O. Emery, and M. Rubin

1965. Ancient Oyster Shells on the Atlantic Continental Shelf. Science, 147:398–400.

Stamp, W. R.

1953. Underwater Television. Scientific American, 188:32–37.

Stanley, D. J.

1971a. Bioturbation and Sediment Failure in Some Submarine Canyons. Vie et Milieu, supplement 22, 541–555.

1971b. Fish-produced Markings on the Outer Continental Margin East of the Middle Atlantic States. Journal of Sedimentary Petrology, 41:159–170.

Stanley, D. J., P. Fenner, and G. Kelling

1972. Currents and Sediment Transport at the Wilmington Canyon Shelfbreak, as Observed by Underwater Television. Pages 621–644 in D. J. P. Swift, D. Duane, and O. H. Pilkey, editors, Shelf Sediment Transport: Process and Pattern. Stroudsburg, Pennsylvania: Dowden, Hutchinson & Ross.

Stanley, D. J., and G. Kelling

1968. Photographic Investigation of Sediment Texture, Bottom Current Activity, and Benthonic Organisms in the Wilmington Submarine Canyon. U.S. Coast Guard Oceanographic Report, 22: 95 pages.

Appendix

PAGES 17–28

Data recorded on videotape at 26 stations, outer continental margin near Wilmington Canyon (period 12 to 16 July 1968 on USCGC Rockaway cruise RoS₄). See Figure 1 for station location.