Monday, July 27, 2009

A few inches of topsoil and the fact that it rains

The meteoric rise of the Incan empire between 1400 and 1532 was driven by a sustained period of warmer weather, new research on Peruvian lake sediments suggests.

The higher temperatures, starting around 1150, ended thousands of years of cold aridity, and enabled Incan farmers to build mountainside terraces for growing crops at altitudes previously too cold to support agriculture.

The extra warmth, lasting around 400 years, also supplied extra water for irrigation in the shape of melt-water from Andean glaciers at higher altitudes.

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