Iain Stewart tells the story of James Hutton, the founding father of geology. This Scottish thinker overturned ancient beliefs about how and when the world was formed.

Iain Stewart finds out how gung-ho geologist Edward Bailey discovered that Scotland was once home to super volcanoes. Plus the story of unsung hero Arthur Holmes.

In the final episode of the series, Iain Stewart finds out about daredevil scientist Louis Agassiz, who first imagined the world had been gripped by an ice age.