Professor Iain Stewart joins the Edinburgh Geological Society to look at scratches in the rocks of Blackford Quarry. In 1840 Swiss geologist Louis Agassiz argued that these had been made by ice, and that the shape of Edinburgh Castle's rock and the Royal Mile had been formed by ice. Animation is used to show how ice was forced round the hard rock to form the crag and tail.

This clip is from:
The Big Freeze
First broadcast:
14 December 2010

This can be used to show pupils evidence that Britain was once totally covered in ice.