Quaternary

The last two million years

The main geological activity during the Quaternary period in Scotland has been the shaping of the existing rocks and landscape by ice.

Scotland hasn’t always been in the same position on the face of the Earth, neither has it always had the same outline. This map shows how ‘Scotland’ may have looked during a Quaternary ice age. Scotland’s present outline has been drawn on the map to help you visualise where the ice sheets were in relation to the land and sea.

This map is a schematic reconstruction of what Scotland MAY have looked like at a particular point during the Quaternary – it is only a representation of Scotland’s ancient palaegeography, not the most accurate scientific palaeogeographic reconstruction. (c) Image reproduced by kind permission of The trustees National Museums Scotland

At times throughout its history, large parts of the Earth have been covered by vast ice sheets. The Quaternary has been one of these periods in time. Ice ages have come and gone repeatedly with the last major ice age in Scotland peaking around 18,000 years ago. Ice sheets more than 1 km thick flowed across the country, scraping rock, gouging u-shaped valleys and eroding mountains. We can see the results of this erosion in almost every part of the country. We also see features that formed as the eroded material was laid down and deposited by the ice. They include boulder clay that covers many parts of the country, and erratics, which are the often-large blocks of rock that have been transported over a distance before being ‘dropped’ by the ice, leaving them scattered on the surface of the land.

The ice sheet weighed heavily on the land, pushing it down. After the ice had retreated and melted, the removal of its weight meant that the land slowly began to rise back up again at a rate of a few millimetres a year, and is still rising. Around the country, we see evidence of the land having risen up at raised beaches – strips of land above the current coastline that were once wave-eroded shorelines.

As for Scotland’s global position, it is currently still heading north and it is predicted that it will continue to do so over the next 200 million years or so.