Cuillin range. Cracks and fissures in the rock provided pathways for later magma intrusions, leading to dykes of basalt which are commonly seen across Skye. The Red Cuillin also have volcanic origins, being formed from a later intrusion of acidic, granitic rock. This granite was more uniformly eroded by wind and water than the gabbro and basalt, causing the red hills to have smoother outlines. The Cuillin provide classic examples of glacial topography and were the subject of an early published account by James Forbes in 1846 (who had become a fellow of the Royal Society of Edinburgh aged only nineteen).
Cheviot Hills they are separated from the Cheviot Hills by the Tyne Gap, part of which lies within the southern extent of the Northumberland National Park. The Cheviot Hills are primarily associated with geological activity from approximately 480 to 360 million years ago, when the continents of Avalonia and Laurentia collided, resulting in extensive volcanic activity (the Caledonian orogeny) which created a granite outcrop surrounded by lava flows. The area enjoys a general right to roam under both the English Countryside and Rights of Way Act 2000 and the Scottish Land Reform (Scotland) Act 2003. The Southern Cheviots include the Otterburn Training