 Most of the Voronezh Massif is covered with thin layers of sedimentary deposits of the Devonian, Jurassic, Cretaceous, and Paleogene periods.In the southeast along the Don River between the cities of Boguchar and Pavlovsk (both in Voronezh Oblast) the crystalline layers come to the surface.On all sides of the upland the Precambrian deposits descend far below the sedimentary layers.