Geology Site Account

Patterned ground is a term used to describe the distinct geometric shapes such as ice wedge polygons that form due to alternate freezing and thawing of the ground in extremely cold or periglacial regions such as the remote regions of the Arctic today. The phenomenon is related to frost-heaving which occurs when wet, porous soils freeze and expand. The coldest part of the most recent glaciation, the Devensian, occurred 20,000 to 25,000 years ago and is known as the Last Glacial Maximum. At this time the ice sheet extended only as far south as Norfolk but the extremely cold temperatures throughout Essex have left their mark on the landscape in the form of patterned ground. At the end of the Devensian glaciation, 10,000 years ago, the patterns were preserved in the ground and are sometimes revealed as crop marks in fields of crops during hot, dry summers.

The Tendring peninsula, and particularly the upland plateau surface surrounding Clacton, is littered with clusters of patterned ground. The networks are visible on aerial photographs by colour contrasts in crops or other vegetation, due to differences in sub-surface drainage. The major proportion and most dense concentration of patterned ground are an area to the west of Clacton and along both sides of the modern Holland Brook and usually within a kilometre of it.

An example of patterned ground revealed by cropmarks in a field at Beaumont. Photo © D. Grayston.