Wednesday, August 29, 2007

Farafra Oasis Daily Photo - Explanation

I posted a couple of photographs of the fabulous White Desert, which lies just to the north of Farafra Oasis in the Western Desert. A couple of people have emailed to ask me more about the formations shown in the photographs, so here's a short explanation.

Although the White Desert is surrounded by limestone cliffs, the floor of the Farafra depression is white chalk (limestone) dating to the Cretaceous. The formations are the result of geological processes that have acted upon this white limestone, removing the somewhat powdery soft layers from the floor and leaving behind them these strange mushroom-shaped cores of rather more reslilient fabric. The mushroom shapes themselves are caused by sand, blown by the wind, which effectively blasts the surviving formations at a few metres above the ground level, creating the "waists" and stems visible in my photographs before eventually underminging the top of the structures completely.
I hope that that helps!

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