Composition and origin of some brickearths on the Chiltern Hills, England

Summary Brickearths, some associated with Lower Palaeolithic industries, occur at several sites on the Chalk interfluves of the Chiltern Hills. They usually occupy funnel- or basin-shaped depressions in the underlying chalk surface and are surrounded and often overlain by reddish flinty clays. Petrographic studies of these silty deposits show they are composed partly of Wolstonian and/or Anglian loess, and partly of silt, clay and sand from Palaeocene Reading Beds or Plateau Drift (largely Reading Beds weathered and disturbed in the late Tertiary and Quaternary). The depressions probably originated as dolines, which were infilled by mixed sediments washed or soliflucted from adjacent land surfaces during several stages of the later Quaternary. Micromorphological evidence suggests that some of the brickearths were affected by development of ground ice, clay illuviation and rubefication before the last major cold stage (Devensian).