
How Scotland's geological foundations came together
A series of continental collisions between 480 million and 425 million years ago brought together Scotland’s five foundation blocks.
A series of continental collisions between 480 million and 425 million years ago brought together Scotland’s five foundation blocks.
About 600 million years ago, the North-west Seaboard, Northern Highlands and Grampian Highlands all lay at the edge of a continent called Laurentia, about 100km or more apart from one another. The Dalradian rocks of the Grampian Highlands were still only layers of sediment building up in the shallows of the Iapetus Ocean south of Laurentia.
The Iapetus Ocean began to open up about 800 million years ago, as the forces of continental drift pulled apart a large, ancient continent. About 500 million years ago, the same forces began to close the ocean once more, bringing together Scotland and England.
The closure of the lapetus Ocean brought about a series of continental collisions known as the Caledonian mountain-building event or Caledonian Orogeny. It was in the lapetus Ocean, as it closed, that the volcanic islands thought to be the foundations of the Central Belt formed.
As the Iapetus Ocean closed, three landmasses were on a collision course with Laurentia:
The collisions that followed during the Caledonian Orogeny formed the Caledonian Mountains, a massive mountain range similar in scale to the Alps or even the Himalayas. The remains of this mountain range stretch from Norway to the Appalachian Mountains of North America.
The Caledonian Orogeny occurred in three stages.
With the completion of the Caledonian Orogeny, about 425 million years ago, Scotland’s geological foundations were finally brought together.