The Loch Doon ‘Granite’ Area, Galloway

Abstract

I. I introduction F our large and several small plutonic masses occur intrusive in the Lower Palaeozoic rocks of the south-west of Scotland, the four large masses being those of the Criffel, the Cairnsmore Q.J.G.S. No. 349B of Fleet, the Loch Doon area, and the Cairnsmore of Cars-phairn. It is the object of the present paper to describe the Loch Doon mass, the intrusions which surround it, and its metamorphic aureole. The Loch Doon mass is intrusive into Ordovician sediments showing the prevalent north-east to south-west strike which was imparted to the rocks of much of the south and west of Scotland by the Caledonian movements. These rocks include Hartfell and Glenkiln beds, represented by grits, flags, and black graptolitic shales, and Arenig beds, which include grits and radiolarian cherts. The district is included in Sheet 8 of the 1-inch Geological Survey map of Scotland. The plutonic rocks occupy a large area extending for a distance of 11½ miles from Loch Doon in the north to just south of Loch Dee in the south, and spread over about 47 square miles. The outcrop is somewhat hour-glass shaped with a maximum width of 6½ miles, and the plutonic rocks are almost everywhere surrounded by high hills composed of metamorphosed Ordovician sediments, which form the Kells Range on the east and the Merrick Range on the west. Both ranges are, for the most part, well over 2000 feet high, Corserine in the Kells Range rising to 2668 feet and Merrick to 2764 feet. Through