Sunday, November 28, 2010

Radar images reveal lost lake


The original article can be found in the December 2010 edition of the journal Geology but be warned that it costs $25.00 for a day's access to the article.

Geologists have found that a huge lake waxed and waned deep in the sandy heart of the Egyptian Sahara.

Tushka region of Egypt is covered by a huge sand sheet today, but years ago, it was home to a lake as big as one of the Great Lakes, said T. Maxwell, a geologist at the Smithsonian National Air and Space Museum in Washington.

Radar images taken from the space shuttle have confirmed that a lake broader than Lake Erie once sprawled a few hundred kilometers west of the Nile, reports Science News.

Knowing where and when such oases existed could help archaeologists understand the environment Homo sapiens travelled while migrating out of Africa for the first time, said team leader Maxwell.

Here's the Abstract from Geology


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 established 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 fish 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. Overflow 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.

No comments: