The name given to blocks of silcia
specific to southern England
Believed to have formed on the surface or in the near-surface of South England during warm phases of the Tertiary period, and broken down by frost action and mass movement.
Characterised as being extremely hard, finely grained, grey to brown sandstone. This stone has been used since prehistoric times, and was used extensively in the construction of Stonehenge.
Also known as greywethers or graywethers.