The glacial strand-lines of Loch Tulla

Abstract

Introduction. Loch Tulla is situated some 23 miles south of Glen Roy at the southern termination of the Moor of Rannoch. It lies in a valley system deeply incised below the general 1000-foot level of the Moor. The Water of Tulla enters on the northeast, and Abhainn Shira from Loch Dochard on the west, whilst the River Orchy issues on the south. The Shira and the Orchy occupy typical Highland glens traversing a mountainous region where summits commonly attain to heights varying between 2000 and 3500 feet. The Water of Tulla is overlooked on its left bank by this same mountainous region, whereas on its right bank there rises the Moor of Rannoch, where summits seldom reach 1500 feet. The Murray-Pullar Survey of the Fresh-Water Lochs of Scotland found Loch Tulla 84 feet deep, with a surface level of 542 feet above O.D. It is not, however, with the present loch that we are here concerned, but rather with its predecessors of late glacial time. Deserted strand-lines can be followed by the eye along the mountain slopes above Achallader Castle. Often these strand-lines seem disappointingly faint, but, when the sun, low in the heavens, illuminates a stretch of the valley-side with grazing incidence from behind, they become conspicuous features of the landscape. They early attracted the attention of Milne (Home),1 who recognised them as lake terraces, and attributed their formation to the swollen waters of Loch Tulla supported for the time being by great barriers of