Ancient Mega-Lake Found in Egyptian Desert

Larry O'Hanlon -

The hyper-arid deserts of western Egypt were once home to a lush mega-lake fed by the Nile River's earliest annual floods.

Fossil fish and space shuttle radar images have defined the bed and drainage channels of the long lost lake, which at times was larger than Lake Michigan, stretching as far as 250 miles west of the Nile in southwestern Egypt.

The discovery pushes back the origin of the "Gift of the Nile" floods to more than a quarter million years ago and paints a drastically different picture of Egypt's environment than is seen today. It also explains the longstanding puzzle of the fossilized fish found in the desert -- fish that are of the same kinds that live in today's Nile River.

It took a lot of staring at the high-resolution radar topographic maps from the 1980s and 1990s -- and tinkering with the colors of those maps -- to make sense of it all.

"It just struck me that: 'Hey, maybe that was the level for the lake,'" said Ted Maxwell of the Smithsonian Institution's Center for Earth and Planetary Studies.

Although the topography is compelling, the evidence by itself isn't sufficient to prove a lake was there or how it was created.

For one thing, there needs to be a source for all the water. That would likely have been Wadi Tushka, a pass to the west of the Nile, which is low enough for the Nile River to have flooded through provided there was more rainfall and larger annual floods than are known today.

Then there are the fish fossils, which are unmistakable evidence for there having been Nile-related water water filling the basin.

There are also archaeological sites, said Maxwell, that help to roughly confine the dates of the lake's surface elevation in more recent times. Maxwell and his coauthors Bahay Issawi and C. Vance Haynes, Jr., published their study in the December issue of the journal Geology.

Despite the radar maps, fish and archaeology, however, there is a lot of evidence that should be there, but isn't, said Maxwell.

Read more...

Posted via http://batavia08.posterous.com batavia08's posterous