Arthur's Seat, Edinburgh

This great dollop of a hill in the centre of Edinburgh is the remnant of an ancient Carboniferous volcano 350 million years old. After it became extinct it was buried, uplifted, tilted and then partially eroded to what you see today. The photographer is standing on more volcanic rocks, another 50 million years older from the Devonian period - that's 400 million years old! I think that is enough of the geology lessons for today.