Aorounga Crater – One of the Best-Preserved Impact Craters in Africa
Aorounga Crater is one of the best-preserved impact craters in the world, located in the Sahara Desert in north-central Chad. This eroded meteorite impact crater is 12.6 km in diameter and its age is estimated to be less than 345 million years (Carboniferous or earlier). One of three craters, Aorounga, is believed to have been formed by the same impact event, while the other two are buried by sand.
A topographic map shows that the outer and inner rings (11 and 7 km, respectively) rise about 100 meters above the mean level. Two relatively flat depressions of uniform width separate the aforementioned rings. Nearly centrally located in the depression is a 1.5 km long hill, possibly an uplift structure. A dark peak or central highland is visible at the center of the crater, which was caused by material splashing up after the impact. There is a small trough filled with sand surrounding this peak. Rocks surround that trough.
Satellite SIR-C radar indicates two nearby circular features surrounding the crater. Aorounga may belong to a chain of craters formed by these impact craters. Aorounga South is sometimes referred to as the exposed Aorounga crater if this hypothesis is correct.
A small circular trough surrounds the highland, or peak, of the crater, which is in turn surrounded by a larger circular trough. The image shows linear rock ridges alternated with orange sand deposits; these geomorphologists call yardangs. A unidirectional wind field erodes exposed rock layers to form yardangs. Sand dunes are actively migrating southwest as the wind blows from the northeast at Aorounga.