104 GENERAL REMARKS, &C. 



to him who shall attempt to form a new arrangement on 

 this principle, than they are difficult of explanation on that 

 which has been here assumed. 



In concluding this article it is proper to remark that 

 this important rock is not limited to the west coast 

 of Scotland. It occurs in the centre of Sutherland, extend- 

 ing in a narrow interrupted line and surrounded with 

 gneiss. It appears also to form a large portion, if not the 

 whole of Caithness ; where it alternates with an argil- 

 laceous schist most commonly of the graywaeke" character. 

 There, it has hitherto been considered as a secondary rock. 

 From the affinity of the Orkney isles to this tract, there 

 is reason to suppose that they are also of similar com- 

 position. In Aberdeenshire also, it appears to have been 

 mistaken for a secondary sandstone ; occurring there in de- 

 tached portions. It remains further to be inquired whether 

 the whole, or part, of the red sandstone of Cromarty and 

 Moray, is not the same ; a circumstance of which there 

 appears little doubt ; although where the two classes of 

 this rock occur together, it would require much caution 

 in drawing the distinction and in ascertaining the common 

 boundary. But I must terminate a discussion already 

 protracted beyond the allotted limits. 



