I read the wikipedia entry (says it’s caused by salt weathering and wind erosion), but could it actually be an old mouth of the Nile?
Reason I ask this is that the shape (see google maps: 30°0′N 27°30′E) and location is very similar in appearance to a river delta and it’s point aligns with the nile at one point.
I’m woefully ignorant of all sciences pertaining to the subject, but I got curious as I looked at that google sat view (looks similar in bing maps too) if it’s even plausible.
Given that it’s well below sea level, the Nile couldn’t have exited to the Mediterranean directly at the depression.
This article suggest that streams once entered and exited the basin long ago, but these were not part of the Nile system.
While I agree that the satellite photo is intriguing in the way that it seems to show a fan-shaped discoloration running from the Nile to the edge of the Qattara escarpment, I would point out that the escarpment, itself, argues against an alluvial plain or a river delta.
The escarpment is fairly solid, not composed of gravel as a glacial moraine would be. River deltas tend to be washed away by the sea or lake into which they empty. I cannot think of any mechanism by which a delta would build up a barrier of solid stone extending more than 60 meters higher than the river itself, that extended 75 to 100 kilometers wide between the “delta” and the Mediterranean. It also fails to explain how the depression was able to dig down to a depth of 133 meters below the Mediterranean.
I could see an argument being made that, at one point, the Nile swung west in a great loop, carving away the base of the northern cliffs. However, that still leaves unanswered the method by which the Nile would have failed to fill the depression with its own great salt lake.
Given that I have found no mention of the Nile in the context of the Qattara, I am going to guess that it is just one more visual coincidence. (Note that maps of the Qattara, itself, show it as an “eyebrow” shape very far from the Nile, regardless of the discoloration between the Qattara and the Nile in satellite photos.)
It wouldn’t have been below sea level during the last ice age.
The overall coloration and pattern seems to suggest the depression was at one time the Nile delta. However, if you travel in the desert west of Baharia Oasis, you will find there is also the “black desert” where the massive sand desert is covered by a coating of black volcanic lava that forms interesting patterns. Plus there’s the white desert a bit further southwest, which seems to be mostly chalk formations (presumably a remnant of an ancient seabed - I have photos of embedded seashells etc. there.
Simply put, the geology and watershed patterns over the past tens of millions (or hundreds of millions) of years may be more complex than simply “the river ran here once.”