15. Brandberg Intrusion, Namibia
The Brandberg is an isolated massif reaching 2606 meters (8550 feet), and rises much higher than any other feature for hundreds of kilometers around. It is composed of a single mass of granite that rose through the Earth's crust some 120 million years ago. Slightly south and to the west of the Brandberg is the much eroded Messum Intrusion. Both of these intrusions reflect a period of extraordinarily widespread geological unrest in the Earth’s history, which preceded the opening of the Atlantic Ocean and the effusion of vast volumes of basaltic lavas of the Karoo formation that form the Drakensberg Plateau. Karoo lavas are exposed immediately to the west of the intrusion. Rocks forced aside by the upward movement of the intrusion are visible encircling the margin of the Brandberg, tilted sharply upward. Ancient gneisses, distinguishable by their lineated texture, are conspicuous along the dry river valley in the center of the frame.
The existence of a set of lavas in South America of the same age and type as those of the Karoo was used for many years by some geologists as strong evidence that Africa and South America had once been united, but their arguments were not accepted until geophysical data demonstrated the reality of plate tectonics.
STS-7, June 1983. Picture #7-23-1248.