130 REMARKS ON THE 



serve an equal constancy, some veins of granite being as coarse- 

 grained as the mass to which they belong. 



In a former part of this paper, I had occasion to notice an 

 alteration which appears to take place in the texture of killas, 

 when in the vicinity of granite. This circumstance was so re- 

 markable in Galloway, at the Louran and other places, that I 

 took the strata so situated, for mica-slate, although I had obser- 

 ved no line of separation between it and the killas ; I was for- 

 cibly struck with this, at the moment, but having then no time 

 to follow it up, I was obliged to leave the country without any 

 particular examination. It will be observed, by the specimens 

 from St Michael's Mount, that the killas there assumes the ap- 

 pearance of fine-gi'ained gneiss. At Wasseldale Crag, between 

 Kendal and Shap, 1 noticed a rock, in the immediate vicinity 

 of granite, quite similar; and I am told, that the texture of the 

 strata, near the granite of the mountains of Morne, is altoge- 

 ther the same. 



This alteration is always of a gradual nature ; and is so im- 

 perceptible, that it affords a good example of what might be 

 understood by the German term Passage, or transition from 

 one species to another ; this Passage, even admitting the sub- 

 stance altered, is of too limited a nature to constitute a distinct 

 and totally different rock. 



This alteration, if traced with attention, may lead to some 

 very important results ; but, without entering upon it at pre- 

 sent, I shall content myself with recommending it to the no- 

 tice of geologists, some of whom may consider it of too minute 

 a nature to deserve attention. They may, however, rest assu- 

 red, that it is only by an accurate examination, and a faithful 

 detail of such objects, that we can hope to arrive ultimately at 

 truth, the only solid basis of philosophic inquiry. 



I may be accused of generalising too much in the foregoing 

 statement, on grounds so limited ; it must be remembered, 



however. 



