September Geology and GSA Today media ...( Earth Consultants International Tustin ...)

Blue Nile incision on the Ethiopian Plateau: Pulsed plateau growth, Pliocene uplift, and hominin evolution
Nahid DS Gani, Energy and Geoscience Institute, University of Utah, Salt Lake City, Utah 84108, USA; et al.

More than three million years ago, early hominins evolved the ability to walk upright and in doing so started us along the evolutionary path that eventually gave rise to Homo sapiens. It was Darwin who first suggested that a change of climate, giving rise to vast, arid, savannahs, may have spurred on human evolution all those millions of years ago. But what caused that change of climate" Could the formation of one of Earths most spectacular landscapes, the Ethiopian Plateau, have been responsible for development of the great African grasslands" And if so, what were the geological processes that led to the formation of the plateau" To answer these questions, Nahid DS Gani of the University of Utah and colleagues turned to some of the most advanced technology that our species has yet produced - the Space Shuttle. By integrating radar topography data collected by the space shuttle with field observations, Gani and colleagues have placed tight constraints on the topographic evolution of the Ethiopian Plateau. Their results indicate that rapid uplift of the plateau began about six million years ago and was related to the development of large shield volcanoes that erupted great volumes of basalt. These findings suggest that plateau formation resulted from the presence of a hot plume of mantle pushing up against the base of the African continent. The timing of plateau formation coincides with
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