Geology
doi: 10.1130/G31320.1
 2010;38;1135-1138Geology
?
Ted A. Maxwell, Bahay Issawi and C. Vance Haynes, Jr.
?
Evidence for Pleistocene lakes in the Tushka region, south Egypt
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GEOLOGY, December 2010 1135
ABSTRACT
Space Shuttle Radar Topography Mission (SRTM) data have 
revealed new details on the extent and geomorphic relations of 
paleodrainage in southern Egypt. Following a period of late Tertiary 
drainage from the Red Sea Hills south through Wadi Qena and west 
across the Tushka region, the Nile River as we now know it estab-
lished its connections with Central Africa and the Mediterranean in 
the middle Pleistocene (oxygen isotope stage, OIS 7 to OIS 5). SRTM 
topography reveals a lake level at ~247 m that is coincident with the 
elevation of middle Pleistocene fi sh fossils 400 km west of the Nile, and 
with the termination of shallow runoff channels in northern Sudan 
that were active during the middle Pleistocene and Holocene pluvial 
periods. An additional lake level at ~190 m is based on the current 
elevation at Wadi Tushka, and is consistent with Paleolithic sites at 
Bir Kiseiba followed by Neolithic sites at lower topographic levels. 
Overfl ow of the Nile through Wadi Tushka during the wetter north 
African climate of the middle Pleistocene, coupled with limited local 
rainfall, was the likely source of water for these lakes.
INTRODUCTION
The area west of the Nile between Aswan and the Sudan border 
is an important key to the evolution of drainage in the northeast Sahara 
throughout the Cenozoic. However, this region has been partially inun-
dated by fi ve lakes at elevations of 132?144 m since 1998 (Abdelsalam et 
al., 2008); the surface has started to host irrigation pivots and associated 
fi elds, and 100 km west of the Nile, the few scattered oases have begun 
to be exploited for their near-surface groundwater. Thus it is important 
to investigate the undisturbed desert surface before it is completely over-
taken. Recent hypotheses for Nile evolution suggest major changes in 
drainage from a pre-Nile southwest direction in the Oligocene?Miocene 
to late Pliocene (McCauley et al., 1986), to northeastward drainage in the 
Pleistocene resulting from establishment of the present Nile (Issawi and 
McCauley, 1992), all of which affected the Kiseiba-Tushka region.
We used Shuttle Radar Topography Mission (SRTM) data at the 
available 3 arc-second (90 m) spatial resolution (see the GSA Data Repos-
itory1) to delineate the topography and surfi cial deposits of the Kiseiba-
Tushka depression, bounded by Kiseiba Oasis on the west, Wadi Tushka 
on the east, the Egyptian western limestone plateau to the north, and the 
gradual southward rise of the desert surface into Sudan (Fig. 1). The 
resulting digital elevation model displays evidence for northeast drainage 
that explains the locations of several oases along the Darb el-Arba?in cara-
van route and the elevation and extent of paleolakes that eventually disap-
peared, leaving numerous remnant playas, some of which were key sites 
for prehistoric humans (Wendorf and Schild, 1998). We present several 
observations of the topography and key geomorphic features based on the 
SRTM data, and hypothesize a new series of fl ood events that may have 
formed middle Pleistocene lakes.
NILE EVOLUTION AND THE WESTERN DESERT
Fluvial activity in the Tushka region was intricately related to the 
timing and direction of overland drainage across the western limestone 
plateau before the Oligocene?Miocene rifting of the Red Sea that initi-
ated formation of the Nile valley (Williams and Williams, 1980). Drainage 
from the Red Sea hills to southwest Egypt (and across Africa) during this 
period was suggested based on the near east-west orientation and junction 
angles of the subsurface paleochannels revealed by Space Shuttle Imag-
ing Radar (SIR) (McCauley et al., 1986). Prior to the establishment of 
the northward-draining Nile, Wadi Qena drained the Red Sea Hills south-
ward through the present Nile valley, and to the west across the Kiseiba-
Tushka depression to combine with the northward drainage from the Gilf 
Kebir plateau, eventually debouching into the Mediterranean (Issawi and 
Osman, 2008).
Sediments of the Nile valley indicate that the present Nile did not 
have a connection with Central Africa before the middle Pleistocene, 
based on the presence of fl uvial sand deposits that extend from Wadi 
eology, December 2010; v. 38; no. 12; p. 1135?1138; doi: 10.1130/G31320.1; 3 fi gures; Data Repository item 2010306.
? 2010 Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or editing@geosociety.org.
*E-mail: maxwellt@si.edu.
1GSA Data Repository item 2010306, data sources and methods, is avail-
able online at www.geosociety.org/pubs/ft2010.htm, or on request from editing@
geosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 
80301, USA.
Evidence for Pleistocene lakes in the Tushka region, south Egypt
Ted A. Maxwell1*, Bahay Issawi2, and C. Vance Haynes Jr.3
1 Center for Earth and Planetary Studies, National Air and Space Museum, Box 37012, Smithsonian Institution, Washington, D.C. 
20013, USA
2Consulting Geologist, 16 Misaha Street, Dokki, Cairo, Egypt
3Departments of Anthropology and Geosciences, University of Arizona, Tucson, Arizona 85721, USA
Figure 1. Digital elevation model of southern Egypt and adjacent Su-
dan derived from National Aeronautics and Space Administration?
provided Shuttle Radar Topography Mission 3 arc-sec data. Middle 
Pleistocene overfl ow of Nile River to the west through Wadi Tushka 
is proposed to account for lake remnants, fossil fi sh, and paleochan-
nel terminations at 247 m and 190 m.
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1136 GEOLOGY, December 2010
Qena across the present Nile valley and the lack of Ethiopian minerals in 
sediments older than the middle Pleistocene Dandara silts (Hassan, 1976; 
Butzer, 1980). The upper part of the Ethiopian mineral-rich Dandara For-
mation has been dated at 213 ka (oxygen isotope stage, OIS 7; Issawi and 
McCauley, 1992), although sediments below that horizon contain a mix of 
Ethiopian and Nubian lithologies.
Current stratigraphic data thus suggest that establishment of the north-
ward-draining Nile and connection with Blue Nile sediments occurred 
over a time period spanning OIS 7 to OIS 5 (~240?100 k.y.). Williams and 
Williams (1980) proposed two models for integrating northward drainage: 
overfl ow of a lake in northern Sudan, or headward erosion of the Nile 
through the uplifted rocks of the Nubian swell. In either case, following 
establishment of northward drainage in the middle Pleistocene, westward 
transport of Eastern Desert sand and gravel across the Nile valley would 
have ceased. Construction of the Tushka overfl ow canal provided access to 
topographic and stratigraphic data suggesting that Wadi Tushka was once 
a tributary to the Nile, draining a large middle Pleistocene or earlier lake in 
the Kiseiba-Tushka depression (Haynes, 1980). Using SRTM topography, 
we can now constrain the extent of such lakes, compare the boundaries 
with other geomorphic features, and speculate on the water source.
TOPOGRAPHIC REMNANTS OF FLUVIAL AND LACUSTRINE 
FEATURES
SRTM topography reveals several previously unmapped drainage 
channels that originate in the Selima Oasis region and drain to the north-
east (Fig. 2). Selima is an uninhabited oasis that was the site of several 
Holocene lakes at 265?285 m elevation, and 10 m above the highest Holo-
cene tufas are limestone benches with well-weathered Middle Paleolithic 
artifacts (Haynes et al., 1989). The lacustrine limestone indicates that a 
small middle Pleistocene lake occupied the Selima depression, and over-
fl ow of that lake to the north explains the source of the paleochannels. Two 
of the larger channels converge 40 km north of Selima, and eventually 
become indistinguishable from the surrounding terrain near Dibis Oasis at 
an elevation of 247 m (Fig. 2).
An even wider valley and set of tributary channels 60 km west of 
Selima consist of a linear northeast-trending valley joined by a 2-km-wide 
curvilinear channel. In combination with northeast-trending furrows at 
22?N, these channels suggest drainage from the southeastern Selima Sand 
Sheet to the southernmost edge of the Kiseiba scarp, marked by Dibis and 
Dibis West Oases (Fig. 2). Prior studies of SRTM topography northwest 
of this area indicated a dominant northeast trend of drainage, including 
both paleochannels detected by SIR, as well as predicted channels based 
on a hydrologic model (Ghoneim and El-Baz, 2007). The channels seen 
here indicate that this northeast slope, and consequent drainage, is present 
farther to the east than previously mapped, and the northeast gradation of 
the channels into the surrounding terrain suggests additional complexity.
We believe that the middle and late Pleistocene drainage was infl u-
enced by repeated Nile fl ooding, following on the working hypothesis of 
Haynes (1985), who suggested a large Pleistocene lake that drained into 
the Nile from what he termed the Kiseiba-Dungul depression. Using the 
elevation of the fossil (Middle Paleolithic) Nilotic fi sh found at Bir Tarfawi 
(Van Neer, 1993) as a base level, the SRTM data indicate that a paleolake 
at that level (247 m) would have fl ooded the entire Kiseiba-Tushka depres-
sion (Fig. 3), and is the same elevation at which the Selima paleochannels 
and other channel remnants to the west blend into the terrain (Fig. 2). We 
interpret the combination of topographic coincidence and ages of Middle 
Paleolithic occupations at Selima and Tarfawi as evidence of at least one 
lake level at that elevation, forming a local base level, reducing the compe-
tence of infl owing streams, and inhibiting channel incision below ~247 m. 
Such a lake would have covered an area of 68,200 km2, and would have 
extended from the Sudan border (22?N) north to the Kharga and Dakhla 
Oases, until dammed by the limestone plateau at 26?N. Including the rela-
tively minor addition of an estimated 25 km3 volume for the Tushka lakes 
as of 2002 (Abdelsalam et al., 2008), the total volume would have been 
?4090 km3. Obviously there has been both regional denudation as well 
as differential erosion of this desert throughout the climate variations of 
the last half of the Pleistocene, so any calculations of volumes should be 
treated as upper estimates.
The elevation of the (pre-canal) Tushka channel at 190 m is an 
additional base level that relates to Kiseiba-Tushka topography. Project 
bore hole records indicate that the bedrock beneath the present canal is at 
123 m; the local Nile channel bedrock is 5 m below that level (Haynes, 
Figure 2. Enlarged portion of digital elevation model along Egypt-
Sudan border showing alignment of (unpopulated) oases from Se-
lima to Bir Ayed along paleochannels. Elevated carbonate benches 
with associated Paleolithic artifacts along northeast margin of Se-
lima Oasis suggest overfl owing lake(s) during middle Pleistocene. 
For elevation legend, see Figure 1.
Figure 3. Extent of lake levels at 247 m (68,200 km2) and 190 m 
(30,400 km2) that would have extended 350 km north from Sudan 
border to Kharga Oasis. Signifi cant middle Pleistocene recharge of 
Nubian aquifer was likely by-product of these lakes, as well as creat-
ing attractive sites for human settlement. For elevation legend, see 
Figure 1.
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GEOLOGY, December 2010 1137
1985). However, two Acheulean hand axes were found in the upper 7 m 
of sediment infi ll of the Tushka excavations; the specimen from the upper 
2?3 m was less abraded than the ax at depth (Haynes, 1980). Such evidence 
suggests that infi lling of Wadi Tushka to near the 190 m level occurred 
prior to the middle Pleistocene Acheulean occupation. This elevation is 
remarkably consistent with the elevations and ages of archaeological sites 
north of Bir Kiseiba, 150 km to the west. There, a 5-km-wide plateau  at 
~200 m elevation has abundant late Acheulean artifacts weathering out of 
the topmost 1?2 m (Haynes et al., 2001). The sand sheet surrounding the 
plateau is at 170?180 m, and is characterized by Neolithic sites (Wendorf 
et al., 1984), scattered Middle Paleolithic artifacts mixed with the lag, and 
several generations of paleochannels (Grant et al., 2004). A lake at 190 m 
would completely enclose the plateau surface (Fig. 3), leaving the two 
sandy alluvial units that contain the artifacts subaerially exposed, consis-
tent with their sand-abraded appearance. This lake would have covered 
30,400 km2 at an average depth of 47 m, and contained 1450 km3 of water.
The northeast alignment and location of the Dibis West?Dibis?El-
Shab?Kurayim?Kiseiba string of oases can now be considered remnants 
of Pleistocene drainage. Although each of these oases is in a local topo-
graphic low, commonly a few meters below the surrounding sand sheet, 
the concentration of groundwater is likely aided by subsurface perme-
able fl uvial deposits (as shown for Bir Kiseiba by Grant et al., 2004). The 
northward topographic gradient likely aided water fl ow toward the chan-
nel thalwegs both during the time of the Selima-Tarfawi lake and during 
the Holocene pluvial, ca. 10?6 ka.
Although the paleochannels north and west of Selima Oasis indicate 
local runoff from rainfall, the middle Pleistocene timing of Bir Tarfawi 
fossils and calcareous benches at Selima allow another hypothesis for the 
origin of the lakes. High discharges in the early Pleistocene coupled with 
continued sedimentation in the upper Nile valley from the Eastern Desert 
in the form of the Qena sand and the Kom Ombo gravels virtually ensured 
that any fl ooding of an early north-fl owing Nile would have been diverted 
into the Western Desert. However, even after the connection of the pres-
ent Nile with Central Africa and channel incision due to sea-level lower-
ing in the middle Pleistocene, it is plausible that Nile fl ooding would have 
topped the drainage divide at Wadi Tushka, fl ooding the Western Desert to 
the levels proposed here. Nile discharge volumes of 300 km3/yr suggested 
for the Holocene wet period (Said, 1993) and late Pleistocene terrace levels 
at 160 m (Butzer, 1980) indicate that older, middle Pleistocene discharge 
could have easily exceeded the 190 m level at Wadi Tushka. Continued 
southward fl ushing of Wadi Qena into the 25 km constriction of the Nile 
valley in the middle Pleistocene would have aided such a process by inhib-
iting throughgoing Nile drainage at the Qena bend. Multiple fl oods to the 
247 m (or higher) level at Bir Tarfawi explain the wide range in U-series 
dates for the various lake phases, and the postdepositional high mobility of 
uranium (Schwarcz and Morawska, 1993). A historical analogy for this pro-
cess is the Holocene history of the Faiyum depression into which the Nile 
overfl owed, forming several lakes during Pharonic times (Hassan, 1986). 
DISCUSSION
This hypothesis of middle Pleistocene lakes is subject to the assump-
tion that the topography derived from SRTM represents that of the middle 
Pleistocene. The gross topographic elements of the sand sheet are likely to 
be retained in this area, as shown by the stability of the sand sheet (Max-
well and Haynes, 2001) and the correlation of SRTM- and SIR-derived 
drainage >500 k.y. apart in age (Ghoneim and El-Baz, 2007). Additional 
sources of uncertainty are the absolute ages and longevity of the proposed 
lakes, and the amount of local precipitation during the middle Pleistocene.
The absolute ages of archaeological assemblages are poorly con-
strained in southwest Egypt (Schild, 1987), and only scattered uranium-
series and optically stimulated luminescence dates in local areas are 
available to determine the timing of carbonate deposition and associated 
occupations that are beyond the range of 14C dating (Wendorf et al., 1993; 
Szabo et al., 1995). Given those caveats, it may still be possible to use the 
location and elevation of archaeological sites to test these ideas. A brief 
review of those sites known to us suggests that several Acheulean and 
Middle Paleolithic artifact locations are found at elevations that straddle 
the 247 m datum. While such equivocal results do not support a long-
standing, monotonically subsiding series of lakes, they are not inconsis-
tent with lakes formed from sporadic fl ooding.
Past attempts to reconcile a Nile connection for middle Pleistocene 
fi sh (Van Neer, 1993) and lacustrine deposits at both Bir Tarfawi (Hill, 
2009) and Dakhla Oases (Kieniewicz and Smith, 2009) have relied on a 
combination of precipitation and groundwater to maintain stable lakes, 
since estimates of 500 mm/yr precipitation (Wendorf et al., 1993) are 
insuffi cient to support a standing body of water. Seasonal (or more fre-
quent) fl ooding of the Nile, particularly during pluvial conditions, may 
well have provided the water necessary for the megalakes proposed here.
CONCLUSIONS
Comparison of a SRTM-derived digital elevation model with geo-
morphic features and scattered archaeological sites and associated sedi-
ments suggests the presence of at least two levels of middle Pleistocene 
paleolakes in the Western Desert. These lakes could have originated from 
overfl ow of the Nile through Wadi Tushka, the low point on the west bank 
of the Nile. An overfl ow origin is consistent with recent hypotheses on the 
origin of the Nile and its integration with drainage from Central Africa.
The sedimentary evidence for these old Egyptian lakes is less com-
pelling than that of the newly defi ned mega?Lake Chad (Leblanc et al., 
2006), the Northern Darfur Megalake in northwestern Sudan (Hoelzmann 
et al., 2001), the White Nile lake in central Sudan (Williams et al., 2010), 
or Lake Megafazzan in Libya (Drake et al., 2008). Nonetheless, the topo-
graphic data add to the growing evidence for numerous early and middle 
Pleistocene lakes across North Africa that could have supported human 
migration patterns.
ACKNOWLEDGMENTS
This research is supported by the Smithsonian Institution endowments (Max-
well) and National Geographic Society grant 7567-03 (Haynes). We thank John 
Grant, Andrew Johnston, Eman Ghoneim, and an anonymous reviewer for their 
comments on this paper, and Martin Williams for a thought-provoking review.
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Manuscript received 21 April 2010
Revised manuscript received 16 July 2010
Manuscript accepted 23 July 2010
Printed in USA
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