Scottish Highlands in the Torridon Hills such as Liathach and Beinn Eighe in Wester Ross. These foundations are interspersed with many igneous intrusions of a more recent age, the remnants of which have formed mountain massifs such as the Cairngorms and the Cuillin of Skye. A significant exception to the above are the fossil-bearing beds of Old Red Sandstone found principally along the Moray Firth coast and partially down the Highland Boundary Fault. The Jurassic beds found in isolated locations on Skye and Applecross reflect the complex underlying geology. They are the original source of much North Sea oil. The Great Glen
Sweet Grass Hills feet), East Butte (with two peaks, the taller of which at 6,958 ft), and Mount Lebanon (5807 ft). The Sweet Grass Hills are an example of the island ranges that dot the central third portion of the state of Montana. These island ranges, completely surrounded by the 'sea' of plains and not geographically (or often geologically) part of the Rocky Mountains to the west, are "biological hotspots", containing more species than the prairie below. The hills were formed in the early Paleogene period, and geologically are known as stocks - intrusive igneous rock forced up from below and solidified. Because