Scotland's geological foundations

The five geologically distinct foundation blocks which make up Scotland were once separate by hundreds of kilometres.

The two most northerly founding blocks the Northwest sea-board and the Northern Highlands appear to have their most ancient foundations in common but are otherwise very different and must have been located far apart at one time. Similarly rocks of the Grampian Highlands are thought to be underlain by rocks comparable to those of the Northern Highlands; but the two areas must have been widely separated for much of their history.

The two most southerly foundations blocks the Central Belt and the Southern Uplands - are both products of the continental drift and continental collisions which brought Scotlands foundations together, and also connected Scotland to England.

The four major faults which divide Scotland's foundation blocks are (from north to south): the Moine Thrust, the Great Glen Fault, the Highland Boundary Fault, and the Southern Uplands Fault. The geological boundary which separates the Southern Uplands from the underlying rocks of northern England is called the Iapetus Suture after the Iapetus Ocean that once separated England and Scotland.

Of these geological boundaries, the Great Glen Fault and the Highland Boundary Fault are the most distinctive landscape features. The Great Glen Fault forms the dramatic gash of the Great Glen, while the Highland Boundary Fault marks the distinctive change from Lowland to Highland scenery. The Moine Thrust, Southern Upland Fault and the Iapetus Suture are less obvious landscape features but are equally important geologically.

Northwest Sea-board

Built from rocks of three very different ages, these foundations include Britain's oldest rocks.

Northern Highlands

Much of the foundations of the Northern Highlands formed around 1000 million years ago in a shallow sea.

Grampian Highlands

The foundations of the Grampian Highlands are predominantly Dalradian rocks, named after the ancient Scots Kingdom of Dalriada in Argyll.

Central Belt

The foundational rocks of the central belt are buried deep, but are thought to be volcanic.

Southern Uplands

The divide between Scotland and England was once a wide ocean. As the ocean closed, the Southern Uplands were formed.