large upland area of the Russian Plain, in the central part of European Russia. It stretches in a north–south direction from the Oka River to the Donets River and the Donets Ridge. The upland has a total north–south length of 600 miles (1,000 km) and a width of 300 miles (480 km), with a maximum height of 950 feet (290 m). In the central part of the upland, near the cities of Voronezh, Oryol, and Kursk, is the Voronezh Anticline; this is a massive upwarping of the underlying Russian Platform and is a geologic base of great antiquity and stability. Elsewhere the Central Russian Upland is overlain by deep deposits of clays, limestones, and sands. The upland forms part of the watershed between rivers flowing to the Black and Caspian seas.