OF LOCHABER. 51 



tops of the little hill of Tom-na-Fersit must have formed two 

 small islands ; and it would depend upon the circumstance, 

 whether Mealderry was, or was not, a portion of the Loch 

 Roy barrier, (which, by the bye, I am rather inclined to think 

 it was not,) whether its top was also an island in the primary 

 or independent state of Loch Spean, or whether it only be- 

 came so afterwards. A reference to Plate VIII. fig. 1. will 

 explain what I suppose to have been the primitive state of 

 Lochs Gluoy, Roy, and Spean. I conceive that Loch Gluoy 

 always remained an independent lake up to the period of its 

 final evacuation : but it is evident, that some intermediate 

 changes took place as to the circumstances of the other two 

 lakes ; and these will now fall to be considered. 



I believe it will be readily admitted, that it is much easier 

 to suppose the existence of former barriers, than to discover 

 the means which operated in their removal ; but it must be al- 

 so granted, that the difficulty of accounting for the destruction 

 of such large masses, does not by any means imply that they 

 never had any being at all, particularly where a number of 

 facts remain to lead us to an opposite conclusion. From all 

 the present appearances, it is extremely probable, that the bar- 

 rier of Loch Roy, was not only very thin, but of soft materials, 

 at the two parts which have been removed. When we consi- 

 der in addition to these circumstances, that the level of Loch 

 Roy was about two hundred and eighty feet above that of 

 Loch Spean, and that, consequently, the pressure against this 

 weak barrier must have been very great, it will not ap- 

 pear by any means very improbable, that some partial rup- 

 ture may have taken place at one, or perhaps both of the nar- 

 row necks A and B, Plate VIII. fig. L, so as suddenly to re- 

 duce the level of Loch Roy to Shelf 3d, where it continued to 

 remain for some time. It is proper to remark here, what I 



e 2 trust 



