The Richat Structure in central Mauritania is a stunning geological structure 50 kilometers across (Wikipedia entry). Once thought to be an impact crater, it is actually a sedimentary formation that has eroded flat over many eons. Apparently there’s a hotel smack-bang in the middle of it.

There are also several other similar structures in the Sahara, such as the Jebel Uwaynat (thumbnail #2) which was used to define the borders of Sudan, Egypt and Libya, and also the Brandberg Intrusion in Namibia.

Even though none of these features are in high-resolution, it’s well worth zooming in a bit, as they’re perhaps even more fascinating to look at closer up.

Thanks to Pat Scaramuzza, Peter Nordstrom, GeMatt and Kai Huebner.

Check out these bizarre circles of farmland smack-bang in the middle of the Libyan desert. This unlikely-seeming sight has been made possible by the construction of the Great Man Made River, possibly the largest water transport system ever built, consisting of a network of pipes buried underground, each four meters in diameter. In the 1960s, efforts to find oil in southern Libya led to the discovery of huge quantities of fresh water underground, and today the Great Man Made River carries more than five million cubic metres of that water under the desert, vastly increasing the amount of arable land.

However, I’m told that apparently these sources of water (which were deposited in the ice age) are only likely to last between 50 and 100 years, yet the project is estimated to have cost 25 billion US dollars.

There’s lots more of these circles around to support this theory, but does anyone else think what they’re actually doing is trying to draw a picture of a giant dog?

Thanks to Tom Beddard, Stuart McGlashan, Steve Rot, pixiecrinkle, Mark and Phillip.