Cliff

The White Cliffs of Dover
The Trango Towers in Pakistan. Their vertical faces are the world's tallest cliffs. Trango Tower center; Trango Monk center left; Trango II far left; Great Trango right.
Europe's highest cliff, Troll Wall in Norway, a famous BASE jumping location for jumpers from around the world.

In geography and geology, a cliff or rock face is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually composed of rock that is resistant to weathering and erosion. The sedimentary rocks that are most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs.

An escarpment (or scarp) is a type of cliff formed by the movement of a geologic fault, a landslide, or sometimes by rock slides or falling rocks which change the differential erosion of the rock layers.

Most cliffs have some form of scree slope at their base. In arid areas or under high cliffs, they are generally exposed jumbles of fallen rock. In areas of higher moisture, a soil slope may obscure the talus. Many cliffs also feature tributary waterfalls or rock shelters. Sometimes a cliff peters out at the end of a ridge, with mushroom rocks or other types of rock columns remaining. Coastal erosion may lead to the formation of sea cliffs along a receding coastline.

The British Ordnance Survey distinguishes between around most cliffs (continuous line along the topper edge with projections down the face) and outcrops (continuous lines along lower edge).

The far southwestern aspect of Nanga Parbat's Rupal face, highest cliff (rock wall/mountain face) in the world. The steepest part of the face is 2 km to the northeast. Cliffs are very common in areas where there are river banks and oceans.