216 THE LOCH LOMOND AND OTHEK VALLEYS. 



ally at high levels, it is probable there is or was a 

 certain amount of subterranean drainage from them, 

 yet it seems scarcely likely that it could have accom- 

 plished much of the excavation of the basins. We 

 are therefore inclined to believe, that after the main 

 lines of the valley were laid out by faults or other 

 shrinkage fissures in the underlying strata, marine 

 action, meteoric abrasion, and ice, separately or 

 conjointly, excavated the basin, that during this 

 process other shifts occurred which modified its 

 original form, while subsequent shifts or shrinkings 

 helped to form the remarkable deep holes. It may 

 also be suggested that among the later movements 

 of the surface, the lower portions of the lake may have 

 been lifted higher than the northern part ; or the 

 upper portion may have been depressed more than 

 the south part. That some of the dislocations in 

 connection with this valley are post-glacial, we are 

 strongly inclined to believe. Our examination, how- 

 ever, was too brief and restricted to justify us in 

 coming to a positive conclusion on this point; but 

 the features of the country about the north part of 

 Loch Lomond, and also in the neighbourhood of Loch 

 Katrine, seemed to indicate very recent movements 

 and breaks in the underlying rocks. 



Before leaving this lake-basin it should be pointed 

 out, that if at the time it was a fiord there was an 

 arctic climate, as the fossils found in the raised beaches 



