in Scotland and Parts of England. 247 



manifestly connected with them in respect of cause. Thus, 

 when we eliminate cliffs and other rough parts as only ex- 

 ceptions, and the effect of subsequent weathering and other 

 casual forces, a comprehensive eye cast over the mountain 

 system of Scotland, has no difficulty in seeing the effects of a 

 general abrading agent which has passed over and more or 

 less moulded nearly the whole. 



I am prepared, however, to shew proofs of a general abra- 

 sion in Scotland, compared to which the above can only be 

 considered as adjuvant and subordinate. 



Most students of geology will remember the striking de- 

 scription which Dr M'Culloch gives of the range of old red 

 sandstone mountains which extends for fifty miles along the 

 west coast of Ross and Sutherland. From a platform of 

 upturned gneiss, undulating in outline, and between 200 or 

 300 and 1000 feet above the sea, rise these mountains iso- 

 latedly to the height of from 3000 to 3500 feet above the sea, 

 with wide spaces between, in some of which lie lakes and 

 estuaries. The strata being disposed at a low angle, it be- 

 comes evident that they are the relics of one wide-spread 

 formation, out of which gaps have been cut by some external 

 agent; and hitherto the district has been regarded as a strik- 

 ing example of the process of denudation, and often adverted 

 to as such in elementary books, the agent usually presumed 

 being water. Not one of these mountains, as far as I am 

 aware, advances to the coast or abuts on the sea ; but at Elm 

 Stor, in Sutherlandshire, a small low patch of the sandstone 

 borders the coast and passes beneath the waves, which have 

 cut it into very fantastic forms. 



It seems to me entirely inadmissible that the sea has been 

 the denuding agent in this case, and for the following reasons : 

 — First, On the gneiss platform between the mountains and 

 the coast, we do not see the fragments of sandstone which 

 would be deposited there by such an operation. Second, We 

 have at Holborn Head, in Caithness, and all along the coasts 

 of Aberdeen and Forfarshire, cliffs of old red sandstone abut- 

 ting on the w r aves, and worn by them into deep chasms and 

 caves, with isolated columnar masses here and there left out 



