 It is thought that the country was eventually abandoned as the ice sheet reached its peak, being recolonised as it retreated.By 5,000 years ago it is thought that the British Isles were warmer than they are at present.Among the features left behind by the ice are the glaciated U-shaped valleys of the Lake District and erratics (blocks of rock) that have been transported by ice, including some from the Oslo region and deposited on the coast of Yorkshire.