Abstract
Summary: A general model for pedogenic carbonate development in alluvial sediments is based upon of rates flood sediment accretion versus time taken for particular carbonate profiles to develop. Conclusions regarding rates of Holocene carbonate pedogenesis and the changing morphology and thicknesses of carbonate profiles with time are used to predict critical values of floodbasin accretion rates which would have enabled particular ancient profiles to develop. Local (intra-drainage basin) and regional profiles are separated and a number of models for calcrete genesis are outlined. The presence or absence of particular genetic stages of calcrete may be used as a rough guide to estimate ancient floodbasin accretion rates.