Stormclouds over Penyghent, from Thwaite Scars limestone pavement
Dramatic cumulonimbus storm clouds billow from a deep blue sky over Penyghent, viewed from the sunlit limestone pavement of Thwaite Scars near Clapham, North Yorkshire.
Limestone pavements were formed during the last Ice Age in the Pleistocene period when moving glaciers scoured bare the surface of the underlying limestone bedrock. The classic pattern of clints (blocks) and grikes (fissures) was produced by the erosive action of overlying soil - such as the moraine deposited by the glacier - and the rainwater that permeated it, enlarging the natural faults in the limestone rock.
On Thwaite Scars, some areas of high-level pavement consist of a 'sea' of frost-shattered rock fragments known as 'felsenmeer' or clitter.
Date taken: 30 April 2013.