Recent advances in silcrete research and their implications for the originand palaeoenvironmental significance of sarsens

Sarsens and puddingstones have long been recognised as varieties of silcret e and were, until recently, considered to have formed under hot sub-tropica l or tropical climates in tectonically stable, low relief landscapes during the early Palaeogene. This paper provides a summary of the major advances in silcrete research since the most recent review of sarsen development and focuses upon models of silcrete genesis derived from studies in France, Au stralia and the Kalahari region of southern Africa. These models include si lcretes which formed within soil profiles by pedogenic processes (pedogenic silcretes), those which formed in zones of groundwater outflow or water ta ble fluctuation in association with drainage-lines or in lacustrine setting s (groundwater or drainage-line silcretes), and more complex cases where si lcretes developed through the interaction of more than one set of processes through time (multiphase and intergrade silcretes). Each of these models i s subsequently placed within a landscape context through consideration of a series of ase studies. The implications of this recent research for the in terpretation of UK sarsens and puddingstones are discussed. The importance of identifying the mode or modes of origin of any silicified remnant materi als before drawing any conclusions concerning their age, extent and possibl e palaeoenvironmental significance is stressed.