Geology of Great Britain
The bedrock geology consists of a complex mix of generally older metamorphic rocks. They are overlain by varying sedimentary rocks.  Igneous rocks have been intruded at different times (squeezed through pre-existing rocks). The complexity of Great Britain's geology is due to its having plate tectonic processes over a very long period of time. Changing latitude and sea levels have been important: the rocks have crossed the equator during their time. Continental collisions have affected the geology, with major faulting and folding during orogeny (mountain-building periods). During orogeny, there were volcanoes and metamorphism of existing rocks.