A number of sites have revealed late Glacial fine grained and organic deposits, increasing our knowledge of the distribution of deposits which might contain rare Upper Palaeolithic and early Mesolithic sites. It is now clear that these deposits occur widely in valley bottom locations along the Thames and its main tributaries. Development pressure in the vicinity of Erith and Crayford has led GLAAS to commission a study investigating the survival of middle Pleistocene silt deposits associated with in situ Levallois flint working remains. Early 20th-century mineral extraction for the local brick industry has had a dramatic impact on these deposits, but preliminary results suggest the lower part of the sequence, which is associated with the more important archaeological discoveries, survives intact over much of the area.
