Geological map of the British Isles, with a colour-coded key (right). The geology of the British Isles is extremely varied with rocks from nearly all geological periods. Three rock formation types are shown: sedimentary, metamorphic and igneous. The majority of the rocks in Ireland, England and Wales are sedimentary, with large areas of volcanic and metamorphic rocks in Scotland. The sedimentary rocks are colour-coded by geological period, from most recent to most ancient (top to bottom) in the key. The oldest rocks are in north-west Scotland, the youngest in south-east England. For a more complex map, with rock names and more geological periods, see C015/2656.