 The geology of Southcote includes the Reading Formation — rock strata in the Lambeth Group consisting of clay, silt and sand formed in the Palaeogene period. Bedrock in Southcote is also formed of chalk, with geological surveys also finding flint samples. A map produced by the Geological Survey of Great Britain in 1860 identifies the area as being predominantly Plastic Clay (now known as the Lambeth Group) and chalk north of the river, with flint and gravel samples typical of the Bagshot Formation south of the Kennet. More specifically, the 2000 survey showed different types of gravel, including Winter Hill (variably clayey and sandy), Lynch Hill (sand and gravel with lenses of silt, clay or peat), and head (a polymict deposit usually formed by periglacial solifluction or gelifluction). The survey also identified that much of the land south of the Kennet is "infilled" or "worked" ground; this area was formerly gravel pits and now used for leisure. The British Geological Survey defines infilled ground as "areas where the ground has been cut away then wholly or partially backfilled" and worked ground as "areas where the ground has been cut away such as quarries and road cuttings".
