Geoscience Reference
In-Depth Information
FIG
15.
Boulder clay or till, West Runton, north Norfolk.
The present-day Arctic has much to tell us about conditions and processes in
Southern England during the cold episodes of the Ice Age. Much of the present-day
Arctic is ice-sheet-free, but is often characterised by permanently frozen ground (
per-
mafrost
). When the ground becomes frozen all the cracks and spaces in the surface-
blanket materials and uppermost bedrock become filled by ice, so that normal surface
drainage cannot occur. In the summer, ice in the very uppermost material may melt
and the landscape surface is likely to be wet and swampy. Ice expands on freezing,
and so the continuous change between freezing and thawing conditions, both daily and
seasonally, can cause the expansion of cracks and the movement of material, with cor-
responding movements in the surface of these landscapes. This movement can cause
many problems in the present-day Arctic by disturbing the foundations of buildings
and other structures.
FIG
16.
Artist's impression of Southern England, south of the ice sheet, during the Ice
Age. (Copyright Norfolk Museums and Archaeology Service & Nick Arber)
