Geology of Great Britain
The oldest surface rocks are the isles in north west Scotland. They are more than half as old as the planet. The basement rocks are the Lewisian complex or Lewisian gneiss. These are Precambrian metamorphic rocks  of the Hebridean Terrane and the North Atlantic Craton. These rocks are of Archaean and Paleoproterozoic age, ranging from 3.0–1.7 billion years (Ga).