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Science Forum Index » Anthropology - Paleo Forum » Ancient Qena River in Eastern Sahara
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| simple_language@yahoo.com |
 Posted: Wed Feb 14, 2007 10:49 am |
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Eastern Sahara may have been the cradle of hominids.
Radar rivers in the Eastern Sahara
http://ourworld.compuserve.com/homepages/mjff/rad_rivs.htm
revealed ancient bed of Qena River. The river flowed south,
so it could have been part of annual migration route that
included the Nile River, which flows north. Excavation
revealed human artifacts dating back to the Paleolithic
along with the shells of Zootecus insularis, a land snail
indicative of formerly moist soil and vegetation.
An early (7 mya) hominid (Sahelanthropus tchadensis) was
found there:
http://en.wikipedia.org/wiki/Sahelanthropus_tchadensis
Acheulian cleavers and handaxes were found there:
http://www3.interscience.wiley.com/cgi-bin/abstract/52178
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Excerpt from "The Sahara Paleodrainages"
http://southport.jpl.nasa.gov/reports/finrpt/McCauley/mccauley.htm
We attribute the "radar rivers" of the western Desert to downstream
parts of the Qena System, which consisted of powerful subsequent
streams that flowed southward across eastern Egypt along the west
flank of the Red Sea Range and then south-westward along the southern
edge of the Limestone Plateau into northwest Sudan (Issawi and
McCauley, 1992). Beginning at about 24 Ma, in Neogene time, volcanism
and accelerated uplift occurred all along the Red Sea area, with more
uplift at the northern margin of the Red Sea rift than farther to the
south (Garfunkel, 1988). This uplift, which gave Wadi Qena a gradient
advantage to the south, is evidenced by the bedrock stratigraphy
exposed in the wadi, where as one proceeds northward (upslope within
the wadi) into higher terrain, progressively older rocks are exposed.
The Qena System was chiefly responsible for producing the cliffs along
the southeastern edge of the Limestone Plateau and the broad,
southward opening pediplain that extends from near Aswan into the
Sudan (fig. 1). We believe (McCauley, 1986a) that elements of the Qena
system were able to flow to the west into the Chad Basin and from
there into the Niger River System. Discussions with our French
Coinvestigator, Hugues Faure (Faculty of Sciences at Luminy,
Marseilles, France) indicate that reddened stream gravels of probable
Tertiary age (the "Continental Terminal") have been reported in the
Marhdogoum Gap (fig. 1), one of the probable late-stage streamcourses
to Lake Chad. There is cartographic evidence as well as Spot and
Landsat data indicating that a major river once flowed through this
breach in the Erdi Plateau. Unfortunately, this area was out of range
of SIR-C because of mission constraints. Another probable outlet for
the later stages of the Qena System is the E-W trending Mourdi
Depression, a structural trough that as late as Quaternary time
allowed the passage of waters back and forth between the Chad and Nile
basins (Pachur and Rottinger, in press).
As a topographic divide between Egypt and Chad began to develop, by
uplift and later volcanism in the Darfur region, the Qena System was
forced progressively more westward around the outlying extremities of
the Eocene marine deposits left by the former Tethys Sea. In so doing,
the Qena System formed, by northward lateral erosion, the south facing
edge of the Limestone Plateau (the Sinn al-Kaddab scarp). (The sandy,
beach deposits of the Tethys Sea are well preserved about 200km
farther to the south of the Sinn al-Kaddab scarp across the Red Sea in
Saudi Arabia. We examined exposures of these rocks near the town of
Turabah (Lat 21_ 30'N, Long 41_ 45'E), where they have escaped erosion
by Tertiary rivers). The Qena System must have flowed on successively
lower erosion surfaces before it was beheaded by the headward
(southward) eroding Nile System. The dying remnants of the Qena System
are marked by playa and mud pan deposits near the base of the scarp,
and by buried channels such as those we examined south of Dungul Oasis
(described later in this report). |
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