Paleosol carbonates from trenches excavated as part of a landscape-scale project in Bed I of Olduvai Gorge, Tanzania, were analyzed for stable carbon and oxygen isotopic composition. The ~60,000-year interval (~1.845-1.785 Ma) above Tuff IB records evidence for lake and fluvial sequences, volcanic eruptions, eolian and pedogenic processes, and the development of a fluvial plain in the western margin of the basin. Significant temporal variation in the carbonate ?18O values records variation of local precipitation and supports the shifts in climatic conditions interpreted from the lithologic record. During this period, carbonate ?13C values varied between depositional facies indicating that the paleolandscape supported a local biomass of about 40-60% C4 plants within a mosaic of grassy woodlands and wooded grasslands. The lithologic and stable isotope record in this small lake basin indicates the area was much wetter, with more woody C3 plants, during this interval than is the semi-arid area today. The record also reflects the variation in climatic conditions (wet/dry) documented by other global climate proxies for this time.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.