“…Several escarpments have been distinguished and investigated in the 20th century: Vendian (Nilsson, 1913;Amantov et al, 1988), Cambrian (Martinsson, 1958;Amantov et al, 1988), Ordovician (Tammekann, 1940;Kiinnapuu, 1959;Miidel, 1992), Silurian (Jaanusson, 1947;Aaloe, 1958,;Aaloe & Miidel, 1967), and Devonian (Мейронс е{ а!, 1974; Страуме, 1979). The Sub-Cambrian peneplain was described by Giere (1938) andFromm (1943).…”