Central Belt geological foundations

The Central Belt (also known as the Midland Valley) is bounded to the northwest by the Highland Boundary Fault and to the southeast by the Southern Uplands Fault.

The rocks which form the foundations of the Central Belt are buried by younger rocks. The exact nature of the geological foundations of the Central Belt, therefore, is uncertain. However, fragments of rock which are thought to have been eroded from the foundation rocks of the Central Belt (before they became buried) are largely volcanic in origin. Other pieces of evidence, such as rock fragments brought up from depth by later volcanic activity, geophysical profiles and even evidence from rocks in a similar geological position in Ireland, also suggest a volcanic nature the foundations of the Central Belt.

It is currently thought most likely that the foundation rocks of the Central Belt are the eroded remains of a chain of volcanic islands. These islands collided with the Scottish landmass to the north at the start of the series of continental collisions which eventually brought all the geological foundations of Scotland together.