230 Dr. Mac CullocH on the Hill of Kinnoul. 



a rock in a condition to be bent and incurvated, should by a peculiar 

 application of external force admit of that more continued pro- 

 longation which in certain circumstances would produce a vein. 

 The analogous incurvations indeed, and the evident prolongations 

 which take place among the laminse of mica slate, and in the con- 

 torted veins of granite and quartz which traverse them, offer cases of 

 parallel difficulty. If the solution which I have offered be incom- 

 petent to this purpose, it is only one more added to the numerous 

 unexplained phenomena which are to be found attending the 

 subject of geology wherever we turn our regards : for we can 

 then look to neither of the prevalent hypotheses for an adequate 

 explanation of this case ; the mechanical structure of the schist as 

 indicated by the parallel disposition of the mica, combined with the 

 want of similar mechanical arrangement in the vein, offering a 

 difficulty to the one as great as it is to the other. I speak of a 

 mechanical arrangement in the schistose rocks as if it were admitted 

 by all, because it appears a circumstance attending on many of these 

 rocks, as perfectly demonstrated as any thing of which we have 

 not actually witnessed the creation, can be demonstrated to our 

 senses. 



For the same reasons I speak without hesitation of the displace- 

 ment, fracture, and incurvation of the graywacke which is imbedded 

 in the trap, and in so doing it is not my wish to speak the language 

 of an hypothesis, but to describe a fact, in such terms as can alone 

 convey an adequate notion of the appearances to a mind divested 

 of all hypothesis. If Nature has really produced imitations of 

 mechanical arrangement by processes unknown to us, it is to be 

 wished that the mode in which they have been produced may be 

 shown, either by means of experiments, or by analogies drawn 

 from that science of which the laws regulate the great proceedings 



