Professor Iain Stewart visits the Mortarach glacier in the Swiss Alps. Here, geologist Louis Agassiz gathered evidence in the 1830s to prove that glaciers moved downhill. Prof Stewart re-creates Agassiz's experiment and then shows modern evidence of movement using web-cam images. Stewart is lowered into a crevasse to show the scale of a glacier, then goes into an ice cave to examine boulders embedded in the glacial ice.

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

Use as an example of the evidence for the geographical and geological ideas we take for granted. The evidence for how glaciers move is clearly shown and could be used to enhance any unit of the work of ice. Students could research how Agassiz's methods have been built on and how glacial movement in currently measured. The clip could also be used to help describe how the availability of melt-water encourages movement and how boulders embedded in the ice scour the land beneath.