44 
BATHYMETRICAL SURVEY OF 
strise point S. 15° to 20° E. ; on the north and west slopes of Ben Ledi, 
S. 35° E., and on the crest of that mountain, at a height of 2875 feet, 
the direction is S.E. In like manner the mountains guarding the outlet 
of Loch Katrine are glaciated to the summit. Striae occur on the top of 
Ben Venue at a height of 2386 feet, pointing S. 40° E. ; on Ben An, at 
an elevation of 1750 feet, E. 30° S. ; and on Ben Bhreac, to the west 
of Ben Venue, the direction of the ice-markings is S. 30° to 40° E. 
Again, on the watershed between Loch Voil and Loch Katrine, the 
evidence indicates a south-easterly movement during the great extension 
of the ice. For instance, at various points on Taobh na Coille, at 
elevations between 2000 and 2250 feet, the striae point S. 30° E., and 
on Meall Gaothach, S. 30° E. In the tract immediately to the south- 
west of Loch Katrine the trend of the ice-markiiigs varies from S.S.E. 
to E.S.E. For example, on Maol Mor (2249 feet) about the 2000-feet 
contour-line, to the north of Loch Arklet, the direction is about 
S. 15° E. ; and on the crest of Ben Uaimhe, to the south of that loch, 
S. 10° to 15° E. Eastwards, throughout the tract between Loch Chon 
and the Trossachs, the trend is E.S.E. To the south of the lofty 
heights stretching from Ben Venue towards Ben Ledi, the direction of 
the striae is more easterly, thus showing that the ice, after crossing the 
high ground, was deflected more towards the east (see glacial striae on 
Plate II.). 
The general south-easterly movement of the ice during the great 
glaciation, throughout the lake district of the basin of the Teith, is 
confirmed by the dispersal of stones in the boulder-clay, and by the 
transport of erratics. Many of the boulders have been carried far from 
their source, and are now found on the tops of the highest mountains of 
the district, some even at greater elevations than the parent rock. 
To the east of Loch Lubnaig, on Ben Vorlich, at a height of 3000 
feet boulders of garnetiferous mica-schist are found resting on glaciated 
surfaces of pebbly grit. Again, on the same mountain, at a similar 
elevation, there are erratics of epidiorite and hornblende schist — rocks 
which are associated with the Loch Tay limestone, and which must have 
been transported from lower ground to the north. Similar boulders are 
met with on Stuc a Chroin and on Ben Each. Again, in the boulder- 
clay on the slopes of Ben Ledi, blocks of hornblende schist occur, 
which must have been transported for some distance. On the south side 
of Loch Katrine, between Stronachlachar and the aqueduct of the 
Glasgow waterworks, boulders of quartzite and garnetiferous mica- 
schist, which are foreign to the basin of Loch Katrine, are found in the 
boulder-clay. Eastwards near Brenachoil Lodge, on the north side of 
Loch Katrine, there are blocks of black schist, like that which accom- 
panies the quartzite of central Perthshire, and which has not been 
detected within the catchment-basin of Loch Katrine. These examples 
are sufficient to prove that, during the climax of the glacial period. 
