485 
of Edinburgh , Session 1881-82. 
porphy rites, lie on either side of the former — schists nearest the 
mountain, granites and porphyries next, and schists again between 
the granites and the Nevis, This apparent order may "be ex- 
ceptional, hut it might come to have significance in relation to 
theories of deposit at different times. The lines in which they lie 
slope to the north-west. Many on the low slopes and in the plain 
are of great size, and present distinct marks of striation and 
polishing. The prevalent direction of the larger axis is north- 
north-west and south-south-east. Reference was made to the 
frequent occurrence of cup-like markings on porphyry boulders 
especially, and it was shown how these are formed. In most of the 
boulders described their angle to the horizon was noted, mainly to 
show that boulders may rest on slopes where one could not have 
expected to find them. The angles vary from 5° to 40° 10', and 
the boulders in size from those twice as big as the human head to 
such as are 17 x 5 x 6, or even larger. The girth of one, taking in 
irregularities of surface, is 160 feet. The peculiar forms of many of 
the boulders were traced to cleavage fracture, and drawings of some 
were exhibited. Reference was made to the series of rocks from 
Meall an fSuidhe , north to Qrag Duibh and the Dorney crystal- 
line limestone, and a section was shown. In the comparatively low 
ground above the rocks shown in this section the erratics are all 
rounded and polished, while the boulders of the rocks in the imme- 
diate neighbourhood are angular or subangular. The boulders 
below the part which was shown in section are of gneiss, limestone, 
mica schist, micaceous gneiss, porphyry, light grey, fine-grained 
granite, pinkish granite, coarse grey granite — 'many being much 
polished and almost circular. 
The boulder and shingle-covered face of Ben Nevis, which looks 
down on Loclian Meall an fSuidhe , was closely examined to ascertain 
if, as had been reported, these were true erratics on this part of the 
mountain, but none were found. 
Some general remarks were made in conclusion : — 
1. The peat has been formed subsequently to the deposit of the 
gravel heaps. What is the significance of the fact, that at the bottom 
of many of the gravel heaps a layer occurs of large bullet-like pieces 
of granite and porphyry resembling those at the bottom of the chief 
deposit of peat, Corpach Moss, into which the heaps do not extend ? 
