Abstract

ERTS-1 satellite imagery confirms that, in addition to the main NNE-NNW structures of the rift valley and Afar, ENE-trending lineaments are a basic part of the framework of eastern Africa, both on the plateaus and, though less numerous, on the rift floors. West of both the Eastern and Western Rifts of Africa, large-scale faulting occurs which trends ENE-WSW. The occurrence of ENE-trending lineaments over a large part of eastern Africa and their correspondence in places with known faults, dikes, flexures and joints, indicates they play a fundamental role in the structural evolution of the region. The lineaments may be conjugate fractures, for transcurrent movement is known along some of them or, possibly, they may lie on small circles about the plate tectonic pole of rotation for the African rift system. No single, consistent explanation for the origin of the lineaments is possible on the basis of the data available.