Kiev is located on both sides of the Dnieper River, which flows south through the city towards the Black Sea. The older right-bank (western) part of the city is represented by numerous woody hills, ravines and small rivers. It is a part of the larger Dnieper Upland adjoining the western bank of the Dnieper in its mid-flow. Kiev expanded to the Dnieper's lowland left bank (to the east) only in the 20th century. Significant areas of the left-bank Dnieper valley were artificially sand-deposited, and are protected by dams.