An Isotopic Study of Paleosol Carbonates from Olduvai Gorge

Abstract

The isotopic composition of paleosol carbonates from Olduvai Gorge can be used to give estimates of the paleoclimatic history of East Africa during the Plio-Pleistocene. Oxygen isotopes are indicative of major changes in the isotopic composition of meteoric water, while carbon isotopes are indicative of major changes in the fraction of biomass using the Hatch-Slack (C 4 ) photosynthetic pathway. Three major periods of climatic change in this terrestrial setting occurred at about 1.67, 1.3, and 0.6 myr. These involved major changes in flora as well as major changes in the isotopic composition of meteoric water. Overall, the climate has become warmer and more arid over the past 2.2 myr.