OF UNSTRATIFIED ROCKS AND VEINS. 155 



that we can scarcely hope to find one portion of that 

 surface which was once most elevated above the 

 waters. If in the progress of such extensive de- 

 struction, thus probably acting on the primary rocks 

 at two distinct periods, every vestige of overflowing 

 granite has dissappeared, it is assuredly an event not 

 calculated to exite surprise. 



That granite has in reality furnished a very large 

 part of the materials of the recent strata, is proved 

 by their constitution. Quartz, felspar, mica, and 

 hornblende, are the chief materials of the sandstones, 

 shales, and clays ; nay, the very fragments of that 

 rock are found every where. Even in our recent al- 

 luvial soils they abound ; and it is a question worth 

 considering, whether the granite boulders, of which 

 the immediate origin has so often been vainly traced, 

 are not rather the portions of decomposed conglo- 

 merate strata, or the more durable remains of the 

 alluvial soils on which they now repose. 



In an argument thus made up of probabilities and 

 resting on analogies, it is legitimate to muster all the 

 force that can be adduced. We have yet to learn 

 whether, if the secondary strata were laid bare, the 

 granite might not often be found beneath them and 

 incumbent on the primary ; protected from, at least 

 the second period of destruction, by their covering. 

 It may happen, for example, for any thing that we 

 can prove to the contrary, that this very case may be 

 present in Sutherland, where the secondary strata 

 actually repose on granite. The observations on the 

 junctions of granite and the primary strata are not 

 easy to make, nor are the exposures often very per- 

 fect ; so that this is one of the cases where the diffi- 

 culty of proving a negative leaves conjecture alike 

 open to all. Why may it not be added, that there ib 



