upland region running north-south, about midway between St. Petersburg and Moscow, Russia. The hills are a northward extension of the Central Russian Upland. The ridge is overlain by deposited glacial materials in the form of terminal moraines and other detritus. The Valdai Hills reach a height, near Vyshny Volochok, of 1,125 feet (343 m). Toward the west the hills decline steeply toward the Lake Ilmen lowland, but there is no distinct boundary on the east
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