Mr Milne 07t the Parallel Boads of Lochaber, 361 



and diluvial debris, which was gradually cat away and lowered by 

 the stream which issued from the loch. Accordingly, there exist 

 still, at and near Urchay Bridge, great heaps of unstratified gravel, 

 which clearly present only a remnant of what must have formerly 

 existed. The valley at this place, is a quarter of a mile wide ; and 

 its sides rise far al)ove the required level. 



(2.) In the valley, at the head of which Tyndrum is situated, 

 there are very manifest indications of the beaches of an ancient lake, 

 although the valley is now occupied by only an insignificant stream. 

 At Sti'athfillan church, the lowest terrace is about 50 or 60 feet 

 above the stream, and may be traced continuously for at least a mile 

 down the valley. The stream has cut through this old lake bottom, 

 exhibiting beds of gravel, sand, and clay, which have been deposited 

 and arranged by the water. About 237 feet above this flat, there 

 are, on the sides of the hills on both sides of the valley, traces of a 

 horizontal shelf, which can be distinctly followed with the spirit- 

 level from above Tyndrum village, down the valley by Auchreach 

 farm-houses, Enich farm-houses, and as far as Crianlarich toll. At 

 several places, boulders appear to have accumulated on this higher 

 shelf. Tyndrum is about 740 feet above the sea. 



(3.) Along the margin of Loch Awe, and particularly near Dal- 

 mally, there is a flat or terrace about 40 feet above the present level 

 of the lake ; and which manifestly indicates a subsidence of its water 

 to that depth. 



(4.) Along the margin of Loch Lubnaig, in like manner, there is 

 a flat or terrace about 40 feet above the lake, and which is very 

 visible on both sides. Here as well as in the former case, the flat 

 runs back from near the margin of the lake to the mountains forming 

 one side of the valley ; and the steep sides of which, contrast most 

 significantly with the almost horizontal flatness of the ancient and ex- 

 posed bottom. 



At Loch Lubnaig, the flat can be traced for a considerable way 

 on both sides of the valley, beyond the point where the lake now 

 discharges itself, and, indeed, almost as far as Leny. At this place 

 as well as at Callendar, there exist indications of enormous quantities 

 of gravel, which, before being cut down and carried away by rivers, 

 afforded ample means of blocking up the waters of Loch Lubnaig to 

 a higher level. The quantity of gravel which formerly existed here- 

 abouts, may be inferred from the existence of the following rem- 

 nants. 



About J mile west of Callendar, tliere is a ridge of gravel and 

 sand about 100 yards long, and from 40 to 50 feet high. Near it, 

 there is a conical mound of the same materials, and about the same 

 height, bearing a thriving plantation. The ridge of gravel to the 

 east of Callendar, designated in guide-books as the Roman Camp, is 

 merely a remnant of the ancient gravel-bed with which the whole 

 valley was filled ; and when it contained a lake, of which there are 



VOL. XLIII. NO. LXXXVI. — OCTOBER 1847. 2 A 



