At collision zones, fold mountains will be formed.
- Where an area of sea separates two plates, sediments settle on the sea floor in depressions called geosynclines. These sediments gradually become compressed into sedimentary rock.
- When the two oceanic plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded.
- Eventually the sedimentary rock appears above sea level as a range of fold mountains.
- Where the rocks are folded upwards, they are called anticlines. Where the rocks are folded downwards, they are called synclines.
A view of the Himalayas from Gorak Shep
Fold mountains can also be formed where two continental plates push towards each other. This is how mountain ranges such as the Himalayas and the Alps were formed.