From Jurassic Oxford to Scotland's Himalayas, Alan explores the secret history hidden in the rocks beneath our feet. He discovers how Scotland and England drifted together from their original locations, near the Equator and the South Pole, and finds fossils which reveal that the Yorkshire Dales was once a sea with coral reefs. The volcanic eruption which created the Giant's Causeway marked the birth of the Atlantic Ocean and the emergence of the British Isles.

• Alan Titchmarsh