Southcote, Berkshire 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
Silt silt appears as a pollutant in water the phenomenon is known as siltation. Silt, deposited by annual floods along the Nile River, created the rich, fertile soil that sustained the Ancient Egyptian civilization. Silt deposited by the Mississippi River throughout the 20th century has decreased due to a system of levees, contributing to the disappearance of protective wetlands and barrier islands in the delta region surrounding New Orleans. In southeast Bangladesh, in the Noakhali district, cross dams were built in the 1960s whereby silt gradually started forming new land called "chars". The district of Noakhali has gained more than of