After the ice:

Enter some Stone Age hunters (18,000 – 10,000BP)

The main objective of the lecture was to trace the major changes of climate, sea level and landscape in Britain following the Devensian ice age. From around 14,000BP we find evidence of Stone Age hunting parties. How were they affected by environmental change?

Scientists are able to use the exoskeletons of beetles as an accurate record of changing temperature in Britain during and after the various ice ages. The data obtained shows that temperatures rose abruptly about 15,000BP. A warm period was followed by a return to glacial conditions during the period known as the ‘Younger Dryas’. Temperatures started to rise again after about 2,000 years. From 10,000BP temperatures became similar to the present day.

At its maximum the Devensian ice sheet extended as far as Herefordshire and there is evidence of one lobe of the ice sheet reaching as far as the Scilly Isles. The thickness of the ice sheet in Scotland may have attained 1.6kms in places but was probably of the order of 500m in Northern England.

At this stage global sea levels were about 130m lower than they are today.

The melting of the ice sheet led to a gradually rising sea level. The most dramatic effects are evident in the area now occupied by the North Sea. At the time of the maximum ice extent this would have been a landmass of low relief. Detailed studies by Birmingham University using seismic data have shown the details of topography in this drowned landscape, which would have been a prime hunting ground.  The response of the British landmass to melting ice and rising sea level is very complex because of the isostatic recovery from depression of the crust by the weight of ice. By 8600 BP Britain had become an island.

The landscape of a retreating ice sheet  is affected by meltwater streaming away from the retreating ice front. The sediments deposited are predominantly sands and gravels although locally short-lived lacustrine environments may develop.

The process of solifluction is very active on hill slopes. These differing environments and sediments were discussed with reference to the Isle of Man where some 14kms of cliffs expose the full spectrum of glacial sediments.

The areas of Britain adjacent to the ice sheet would have been characterized as tundra with ground frozen for most of the year and a very restricted growth of low-lying plants. As temperatures rose early colonisers such as dwarf birch started to establish themselves around 12,000BP but grasses and sedges would have been dominant at that time. From 10,000BP a diverse range of trees and shrubs covered the landscape.

The earliest evidence for the return of hominids is a skull from Gough’s cave at Creswell Crags in Derbyshire which has been dated at 14,700BP. However, most archaeologists consider that the return of hunters on a regular basis began about 13,000BP. The prime target for the hunters at this stage would have been horses although smaller mammals and birds were also eaten. From about 10,000BP the gathering of fruits and nuts would have become a significant part of their life style.

This lecture comes from a series which I am preparing for delivery in January 2014 which will be entitled “The evolution of the British landscape: geological and archaeological perspectives”.

Richard Edwards