Between the South Downs and the English Channel is the South Coast Plain, also known as the Sussex-Hampshire Plain, part of the Hampshire-Dieppe basin, and it owes its level character to the action of marine planation. The plain is occupied partly by chalk and partly by Tertiary rocks, both much obscured by more recent deposits. The Eocene strata lying south of the Downs and west of Brighton - with the exception of some outliers of Reading Beds near Seaford - include the Woolwich and Reading Beds, London Clay (with hard Bognor Rock), the Bagshot and the Bracklesham Beds, which contain many fossils. Superficial deposits cover much of the coastal plain; these include glacial deposits with large boulders, raised beaches, brick earth and gravels, marine and estuarine, and the interesting Lower chalk or Coombe rock, formerly known as Elephant Beds, a coarse rubble of chalk waste formed late in the Glacial period, well exposed in the cliff at Black Rock east of Brighton, where it rests on a raised beach.