ABSTRACT
Detailed analyses of the fine and very fine sand (250–63 μm) fractions in a paleosol sequence on Mount Kenya provide data which allow the development of a detailed lithostratigraphy, as well as interpretations on the origins of sediments in the geologic succession. Paleosol horizons correlate closely with lithostratigraphic boundaries, and SEM photomicrographs provide evidence for weathering histories and different paleoenvironments over the period ~ 100,000 to > 500,000 yr BP. Tills with glacially crushed grains, high contents of ferromagnetic minerals, and low contents of quartz alternate downward in the sequence, with eolian sediments and tephras, containing an abundance of volcanic glass and feldspar with variable degrees of etching, and considerable amounts of quartz. Of all the neoformed clay minerals in this sequence, hallyosite and gibbsite appear to be the primary weathering products reflecting the high precipitation and low evapotranspiration expected in a tropical bamboo forest as well as a great amount of time. Their distribution indicates important changes of weathering conditions and paleoclimate over time.
