140 Charles Maclaren, Esq., on the Existence of 



owing to their immense weight, is extremely steady, that the 

 scratches would generally be straight and persistent in their 

 bearing. • This is, we believe, the best explanation of the 

 phenomena of scratched and grooved rocks in level countries, 

 which geology has at present to offer. 



This view of the subject may perhaps suggest a doubt 

 whether the scratches and groovings at Gare Loch may not 

 be attributed to icebergs rather than glaciers. It must be 

 kept in mind that an iceberg is, in many cases, nothing else 

 than the outer portion of a glacier terminating in the sea, 

 which breaks off from the mass and floats away. There are 

 appearances which indicate, that when the strise were made, 

 the sea stood considerably higher in the valley than it does 

 at present ; and thus glaciers and icebergs might be con- 

 joined in producing these marks. My reasons, however, for 

 thinking that the striae are due to glacier action are these : — 

 First, an iceberg detached, we shall suppose, from the group 

 of the hills at I, (Fig. 2,) and moving southward, if it floated 

 high enough to clear the elevated land at ^, (see Map,) would 

 not have touched the rock in the lower part of the valley at all. 

 Secondly, if an iceberg was the agent, the higher ground 

 should have been more deeply furrowed and grooved than 

 the lower, while the case is just the reverse. The striae, 

 which are deep, numerous, and distinct near the level of the 

 sea. become fainter and fewer as we ascend, and disappear 

 altogether at a moderate height. Thirdly, the long bank of 

 gravel p q, fig. 1, if it be a terminal moraine, proves that a 

 glacier once occupied the valley above it. 



That icebergs existed and acted here, however, seems to 

 me extremely probable. It is remarkable, that while the 

 mountains beyond Loch Long and Loch Lomond, M K I H E, 

 are exceedingly rough in the surface, carbuncled all over 

 with bare rocky protuberances, and have a serrated outline 

 singularly bold in its indentations and salient points, the 

 ridges ABC, within the peninsula, exhibit an appearance 

 exactly the reverse. Their sides are comparatively smooth, 

 and much more covered with peat and turf, while their sum- 

 mits are either straight lines or gently undulating curves. 

 The contrast in the outward aspect of the two sets of hills is 



