It is certainly derived, through Rossiya, from Slavonic Rus or Ros (Byzantine `Pws or `Pc o-oc), a name first given to the Scandinavians who founded a principality on the Dnieper in the 9th century; and afterwards extended to the collection of Russian states of which this principality formed the nucleus.
Russia they form the floor upon which lies a thin covering of Tertiary beds, and they are exposed to view in the valleys of the Dnieper and the Bug.
Over a large part of this area, however, they are concealed by the later Tertiary deposits, and they are absent over the Dnieper and Don ridge in the Yaila Mountains and in the higher parts of the Caucasus.
This swelling includes the Donets coal-measures and the middle granitic ridges which give rise to the rapids of the Dnieper.
Below Ekaterinoslav the Dnieper flows for 46 m.