![Top curves](../../../../jsp/jahia/templates/GSL/gsl_templates/img/keystage3/main_top_grad.gif)
Freeze-thaw
Where does it occur?
In mountainous regions like the Alps or Snowdonia.
How does it occur?
Rainwater or snow-melt collects in cracks in the rocks.
![Downwards pointing arrow head](../../../../webdav/site/GSL/shared/images/education_and_careers/RockCycle/Processes/Weathering/Downwards%20arrow%20head.jpg)
At night the temperatures drops and the water freezes and expands.
![Downwards pointing arrow head](../../../../webdav/site/GSL/shared/images/education_and_careers/RockCycle/Processes/Weathering/Downwards%20arrow%20head.jpg)
The increases in volume of the ice exerts pressure on the cracks in the rock, causing them to split further open.
![Downwards pointing arrow head](../../../../webdav/site/GSL/shared/images/education_and_careers/RockCycle/Processes/Weathering/Downwards%20arrow%20head.jpg)
During the day the ice melts and the water seeps deeper into the cracks.
![Downwards pointing arrow head](../../../../webdav/site/GSL/shared/images/education_and_careers/RockCycle/Processes/Weathering/Downwards%20arrow%20head.jpg)
At night the water freezes again….etc.
![Rocks broken by freeze-thaw action, Snowdonia.](../../../../webdav/site/GSL/shared/images/education_and_careers/RockCycle/Processes/Weathering/freezethaw1.jpg)
Rocks broken by freeze-thaw action, Snowdonia.
When the rock is finally broken in to small pieces they collect at the bottom of the mountain. The piles of broken rock are called scree.![Scree at Wastwater, Cumbria.](../../../../webdav/site/GSL/shared/images/education_and_careers/RockCycle/Processes/Weathering/freezethaw2.jpg)
Scree at Wastwater, Cumbria.
![Bottom curves](../../../../jsp/jahia/templates/GSL/gsl_templates/img/keystage3/bottom_curve.gif)