184 On the Granite formation 



northward ; but I do not find mention made by any writers 

 of granite veins in these formations, but still it appears to 

 me that the points of difference are so considerable as to 

 permit ground for the supposition that the granite of India 

 may be the true granite, and should be assumed as the type 

 or normal of that formation ; while the granite which occurs 

 in Great Britain, and such as we have the best description of, 

 may not be itself the lowest and basic formation, (as indeed 

 is known by volcanoes being ejected from beneath it,) and 

 that the phenomena of its intruded veins and metamorphic 

 action, may have been caused by the fusing power of some 

 other formations on which it rests ;* of which also evidence 

 may be derived from the fact of slate veins being intruded 

 into granite, as well as the veins of granite into the slate, 

 vide Boase and other authors. 



Dr. McCulloch (Geology, vol. i. p. 161) remarks upon the 

 desquamation of the Scottish granite, and that of Africa ; a 

 fact which is corroborated by another writer (Phillips) I think, 

 who observed it in the balusters of a bridge. In Indian 

 granite, however, this phenomenon is quite unknown, nor 

 does it occur in any other rock ; for it will be shewn elsewhere, 

 that what has been supposed by some to be the desquamation 

 of spheroids of trap, is an original structure in the rock. 



Derivation origin. 



As the syenite and porphyritic syenite, and other rocks 

 found embedded in granite occur, forming a large proportion 

 of the schistose series, and as quartz rock and pegmatite, 

 and in short all the minerals and rocks necessary for the 

 formation of granite are there found in beds, it is plain that 

 to disintegrate the components of the granite, and re-arrange 

 them in beds to form the schistose series, would be a some- 

 what too improbable theory. It seems most probable, there- 



* Or it may be in fact only a variety of a trap rock, and such appears 

 to be the opinion of Phillips, Encyclopedia Metropolitana. 



