52 
BATHYMETRICAL SURVEY OF 
the direction of the strise is E. 20° S., which coincides generally with the 
long axis of the loch. Heference has already been made to the more 
easterly movement of the ice as it left the mountainous region and 
approached the low-lying districts; the course of Loch Ard coincides 
with this easterly trend of the ice. 
From the evidence adduced it is obvious that the geological structure 
of the basin of Loch Ard has had an important influence in the develop- 
ment of its present features, the latter being adequately explained by 
the theory of glacial erosion. 
The Lake of Menteith lies in various superficial deposits, composed 
partly of boulder-clay and stratified beds of the 100-feet beach. It is 
within the area occupied by the Old Hed Sandstone, and the solid rock 
is visible only at one locality, at Coilledon. Loch Leven likewise lies in 
superficial deposits. 
