Permian to Cretaceous Scotland 299-65 million years ago

The Permian period, between approximately 299 and 250 million years ago, was warm and dry. Scotland had drifted to the sub-tropical zone north of the equator, and desert conditions prevailed. Sediment was blown around by the wind and re-deposited in the form of sand dunes. There was also a lot of active faulting in the Permian in response to continued extension of the Earth's crust in southern Scotland. The desert conditions extended into the Triassic, but by the Jurassic around 200 million years ago (when Scotland lay at a similar latitude to the Mediterranean Sea today), a shallow tropical sea covered most of Scotland. There was an abundance of sea life, including corals and ammonites. On the surrounding land there was an ecosystem that included dinosaurs.

During most of the Cretaceous (145 to 65 million years ago), Scotland was dry land. However, by the Late Cretaceous around 75 million years ago, all but the very highest areas of Scotland was submerged beneath a tropical sea. Thick layers of chalk were deposited on the sea floor. We do not see much evidence of the chalk today as much of it has since been eroded away.

Today areas of Permian, Triassic, Jurassic and Cretaceous rocks in Scotland are relatively small. The largest areas of Permian and Triassic rock are found in the Southern Uplands (Permian) and on Arran (Permian and Triassic). Other significant areas occur in Ayrshire (Permian), the south shore of the Moray Firth (Permian and Triassic) and Lewis (Permian and Triassic), with smaller outcrops elsewhere including Rum, Mull and Applecross.

The small areas of Jurassic and Cretaceous rocks that exist in Scotland are confined to the east and west coasts. The largest areas are around Helmsdale on the east coast and Skye - 'Scotland's Dinosaur Isle' - on the west coast.