Other Landforms

Along irregular coastlines, joints and other weaknesses in headlands tend to be exploited by the waves to form caves of various shapes and sizes.

These caves may eventually be eroded back through the headland to form an arch.

Continued erosion and weathering will eventually weaken the arch so that it collapses to leave behind a pillar of rock or stack.

Ultimately the stack will be reduced to a stump and eventually disappear.

Sometimes the sea cuts inland along a joint or fault line to form a narrow, steep-sided inlet called a geo.

In well jointed rocks, the sea may erode vertically at the back of caves to form a blowhole.

Blowholes and cliff slumping

This video looks at blowholes which are vertical faults which have been widened by wave attack. Headlands are made up of hard rock and bays formed where softer rock erodes away more quickly. Sub-aerial processes, such as rainfall, can also cause erosion. This often happens where layers of boulder clay, left behind by melting glaciers, become saturated and cause the cliff to slump.