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Central Belt: geological foundations

The rocks that form the Central Belt’s foundations are buried beneath younger rocks, so their exact nature is uncertain.

Fragments of rock thought to have been eroded from the Central Belt’s foundation rocks before they became buried are largely volcanic in origin, however.

Other evidence backs up the belief that the foundations of the Central Belt – also known as the Midland Valley – are volcanic in nature.

This evidence includes:

  • rock fragments brought up from depth by later volcanic activity
  • geophysical profiles
  • evidence from rocks in a similar geological position in Ireland

It’s currently thought that the foundation rocks of the Central Belt are most likely 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 that brought together Scotland’s geological foundations.

The Central Belt is bounded by the:

  • Highland Boundary Fault to the north-west
  • Southern Uplands Fault to the south-east