484 
Proceedings of the Royal Society 
between the Nevis and the Spean. It varies in thickness from a 
few inches to 1 6 feet. In a general way, when looked at in section, 
a layer of coarse sand and gravel, with lumps of bulletdike granites, 
porphyries, porphyrites, and mica schists, lies on the rock ; higher up, 
beds of coarse sand, on the top of which are stones not generally so 
much rounded; above this the peat. It many places the remains of 
trees are abundant. Occasionally thin beds occur almost as fine in 
the grain and as hard as lignite. It was shown that the level of 
Corpach Moss is yearly becoming lower. 
II. Sand and Gravel. — These are met within irregular ridges, 
in long undulating mounds, in short squat heaps, and in conical 
hillocks. The Auchindall hills determine, to a large extent, the lie 
of these heaps. Section, beginning below — (a) rolled stones and 
gravel, stones about twice the size of the head ; (6) waved sand ; 
(c) fine gravel; (d) waved sand ; (e) horizontal bed of sand ; (/) peat ; 
(g) surface soil. It was shown that the deposits left on the shore, 
after an exceptionally high tide had met the Lochy in flood, bear great 
resemblance to many of these heaps, excepting the marine debris. 
III. Angular Debris on the Mountains. — This was described, 
and it was asked — (1) Are the angular boulders, and the angular 
debris which often accompany them, of the same age, and expressive 
of the same forces 1 (2) When both angular and rounded boulders 
accompany the debris, must we co-ordinate the former with the 
angular debris only 1 
IV. Boulder Heaps or Clusters. — These terms were chosen in 
preference to lateral, medial, and terminal moraines, morainic matter, 
morainic aggregations, and the like, which were held to be mis- 
leading at this stage of the inquiry. A typical boulder heap, near 
the foot of the south-west slope of Meall an fSuidhe, was described 
and represented by a drawing. Drawings were shown of circular 
heaps high up the mountains, and their chief features were pointed 
out. 
V. Single Boulders. — These were fully illustrated by a series of 
drawings. Several of them bear a strong resemblance to the fine- 
grained pinkish granites near Loch Ness. Of the boulders which 
lie near but not in the heap now mentioned, those of granite, 
granitic porphyry, and porphyry, lie for the most part in a line of 
their own, while those of mica schist, micaceous gneiss, and some 
