coastal cliff

Cliffs in coastal areas are produced by erosion. Steep cliffs, such as these on the Cape Peninsula, in the Western Cape province of South Africa, occur when the sea removes all the material eroded by the waves. In other places, if erosion is rapid but transport is limited, material builds up, and a low-angle slope develops.

Waves on the Isle of Purbeck, Dorset, pound away at the coast, and as the chalk is worn away steep cliffs are formed. The lack of rubble at the base of the chalk is due to its removal by high-energy waves. This area of coastline was initially eroded because these were low-lying valleys; a remnant of the valley is seen here, as a low point on the chalk valley. Today it is a dry valley – a valley without a river – and is known as Scratchey Bottom.

Cliffs on Portland Island, Dorset, England. Jointed rocks, such as the limestone shown here, are vulnerable to erosion, especially along the joint. In this photograph, the dark shadow in the centre marks a geo, a steep inlet opened up by the force of the sea. On top of the limestone there are beach deposits. They were deposited about 125,000 years ago under different climatic conditions, when the sea level was higher.

Columns of basalt at the coastal resort of Vik, in southern Iceland. These angular formations of igneous rock are created during cooling when contraction of the material produces joints which form a hexagonal pattern. Another example of such basalt formations is the Giant's Causeway in Northern Ireland.

The lonely cliffs of western County Cork, in the Republic of Ireland, offer an undisturbed habitat for a variety of rare flowers. Temperatures here are mild, and there is a high average rainfall.

Sandstone outcrops with an east-to-west alignment form the rugged cliffs, deep bays, and long inlets of County Cork on Ireland's southwest coast.

Bedruthan Steps on the north Cornish coast in England. Erosion of the cliffs has left massive rock stacks standing in the sea. This site is managed by the National Trust, and the cliff-top walk is part of the 800 km/500 mi Southwest Peninsula Coast Path.

Steep slope rising from the sea to a considerable height, and consisting of either bare rock or an accumulation of deposited material such as clay. The nature of the cliff depends on a number of factors such as the nature of the rock (its strength, weaknesses in the rock and bedding planes), its exposure to waves, and whether any coastal protection measures have been used.

Limestone has a well-developed jointing and bedding structure and forms geometric cliff profiles with steep, angular cliff faces, and flat tops. Coastal erosion causes complete blocks to fall away resulting in angular overhangs such as those at Tresilian Bay, Llantwit Major, Wales. The rate of cliff retreat is much more rapid in chalk, and steep cliffs are created by erosion and landslides. Cliffs can also be found in areas of softer rock such as the clay cliffs of Norfolk and Holderness, England.

The dip of rock bedding planes also affects the cliff profile. If beds dip vertically, a sheer cliff face will be formed, as at the Old Red Sandstone cliffs in Dyfed, Wales. If they dip steeply seaward then steep, shelving cliffs will occur, as at the cliffs at Tenby, Wales.