HORST, the term used in physical geography and geology for a block of the earth’s crust that has remained stationary while the land has sunk on either side of it, or has been crushed in a mountain range against it. The Vosges and Black Forest are examples of the former, the Table, Jura and the Dôle of the latter result. The word is also applied to those larger areas, such as the Russian plain, Arabia, India and Central South Africa, where the continent remains stable, with horizontal table-land stratification, in distinction to folded regions such as the Eurasian chains.