Geology.

Abstract

Traces the evolution of the Sahara landscape from its origins in the Precambrian to the effects of climatic change in recent years. The tectonic setting is provided, and comments are made on stratigraphy and sedimentation: middle Tertiary uplift initiated a phase of widespread erosion, and sandy detritus was ferried by major rivers into closed sedimentary basins. Towards the end of the Tertiary, wind-blown sands made their first appearance in the Chad basin. The impact of vulcanism and other igneous activity is shown, and the geological effects of desiccation and climatic fluctuations are mooted.-P.J.Jarvis