STS058-88-017 (18 Oct-1 Nov 1993) --- The eye-catching "bullseye" of the Richat Structure adds interest to the barren Gres de Chinguetti Plateau in central Mauretania, northwest Africa. It represents domally uplifted, layered (sedimentary) rocks that have been eroded by water and wind into the present shape. Desert sands have invaded the feature from the south. The origin of the structure is unknown. It is not an impact structure, because field work showed that strata are undisturbed and flat-lying in the middle of the feature, and no shock-altered rock could be found. There is no evidence for a salt dome or shale diapir, nor is there any geophysical evidence for an underlying dome of dense igneous rock having about the same density as the sedimentary layers.

AS08-16-2588 (21-27 Dec. 1968) --- Both sides of the Atlantic Ocean are visible in this view from Apollo 8 spacecraft. (Hold picture with Earth at bottom left). The large, most prominent land mass is the bulge of West Africa. The portion of Africa near the equator is dark and cloudy, but the more northerly portions are clear, showing the prominent cape at Dakar and the Senegal River in Senegal; Cap Blanc; the Adrar Plateau in Mauretania; the wide expanse of desert in Algeria and Spanish Sahara; and the far edge, the Atlas and Anti-Atlas Mountains in Morocco. Clouds cover the eastern coast of South America, southward from Surinam and Guyana to near the city of Salvador, Brazil. The view was photographed following trans-lunar insertion.