Until about 8,000 years ago, Ireland and the British Isles were the westernmost part of the European continent. It all was one great land mass until the lands off the current European West Coast and surrounding the British Isles went beneath the waves. These sunken lands now are called Doggerland.
Scientists at St. Andrew's University have produced an interesting map of Doggerland as it was, including the locations of known settlements. They also have made a number of graphics showing how Doggerland looked in their opinion.
The International Business Times has the map and a good report at:
I haven't found an English language site with the graphics, but then, language isn't too important when you're looking at pictures. The German news magazine Der Spiegel has a photo sequence with the maps and the graphics at: