Mobile cliffs - State 1

Unconsolidated clay (including glacial boulder clay) erodes very rapidly. A combination of rain water seeping through the surface layers and attack at the base of the cliff, which removes the deposited material, can lead to the development of cliffs devoid of vegetation. These most rapidly eroded cliffs occur in the east of England (Holderness) and along the Norfolk and Suffolk coasts. Rates of up to 5m per annum have been recorded in cliffs similar to that shown in the picture below.

Caption: Rapid erosion in boulder clay cliffs on at Sidestrand on the Norfolk coast

The material in the foreground is recently mobilised clay, which has become liquid following a period of heavy rain (picture in spring). Here the cliff erosion processes are at their most active.

In this state the values associated with nature conservation interest are either non-existant or restricted to a few specialised invertebrates (see values for State 2 cliffs). The value of the delivery of sediments to the nearshore zone is much more significant.