Officially named the Richat Structure, this huge circular uprising is located in the Sahara desert. Also known as Eye of the Sahara, Eye of Africa, or Guelb er Richat, scientist once believed it was caused by a large meteorite that once hit the earth, but now believe it is simply erosion that left a large circular print. There are no confirmed theories of why it is circular.
Inside the formation a large assortment of rocks can be found, they include gabbros, rhyolitic volcanic rocks, carbonatites, and kimberlites. It has a diameter of about 40kilometers and is an admired phenomenon.photos taken from: http://earthobservatory.nasa.gov/IOTD/view.php?id=2561
