Geology Site Account
Southend District, SOUTHCHURCH, Bournes Green ice wedge polygons, TQ906871
Locate Bournes Green ice wedge polygons on map
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. Known as periglacial features they include ice wedge polygons which are formed when the ground shrinks and cracks creating a network of ice wedges not unlike the much smaller scale pattern of cracks that often appears on the dried mud on the edge of a lake. Each summer, these giant cracks filled with water which later froze widening the cracks; a process which continued throughout the glacial stage. At the end of the Devensian glaciation, 10,000 years ago, these cracks filled with debris preserving them as ice wedge casts which are sometimes revealed as crop marks in fields of crops during hot, dry summers.
Geology Site Map
Locate Bournes Green ice wedge polygons on map
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. Known as periglacial features they include ice wedge polygons which are formed when the ground shrinks and cracks creating a network of ice wedges not unlike the much smaller scale pattern of cracks that often appears on the dried mud on the edge of a lake. Each summer, these giant cracks filled with water which later froze widening the cracks; a process which continued throughout the glacial stage. At the end of the Devensian glaciation, 10,000 years ago, these cracks filled with debris preserving them as ice wedge casts which are sometimes revealed as crop marks in fields of crops during hot, dry summers.
At Southchurch, on the north side of the Royal Artillery Way (A1159) near Bournes Green, there are fields which sometimes reveal these crop marks. They are a reminder of a time when Essex was an extremely cold, inhospitable landscape.
Aerial photograph of cropmarks that reveal the former existence of ice wedge polygons in a field adjacent to the A1159 at Southchurch. Superimposed on these are cropmarks formed by the square enclosure of a Bronze Age camp. Photo: Edward Clack
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Geology Site Map