208 GENERAL REMARKS [Ch. X. 



also, is here, as in Ireland, the prevailing ingredient in 

 certain places : and the surrounding schistose rocks not only 

 alternate with quartz -rock, which is sometimes in beds of very 

 considerable extent; but all these rocks contain hornblende 

 in various proportions, and this mineral frequently gains the 

 ascendancy over the other ingredients, or obtains to such a 

 degree as to impart its characters, producing greenstones, 

 traps, and other kinds of hornblende-rocks. The granite of 

 Saxony is essentially micaceous : it contains, here and there, 

 hornblende, as in Scotland, but it is not so prominent a 

 feature; and it is succeeded by micaceous gneiss and mica- 

 slate, which likewise possess some occasional beds of horn- 

 blende-rocks. The granite of Mont Blanc is characterised 

 by talc ; and the strata with which it is associated are fel- 

 spathic talc-schist, common talc-schist, and talcose slate, and 

 many species of serpentine, euphotide, and other magnesian 

 rocks. Lastly, the same connection occurs in Corsica: the 

 granite alternating with eurite and protogine, or talcose gra- 

 nite; and the gneiss and mica-slate adjacent thereto are inter- 

 stratified with the same beds, and pass into talc-schist, stea- 

 schist, serpentine, and analogous compounds. 



Other instances of this relation between the granitic and 

 schistose rocks might be adduced ; and these might have 

 been enlarged, not only by pointing out the connection which 

 generally prevails in each district, but by relating the lesser 

 or subordinate appearances of this kind which occur in many 

 parts of the same district. Sufficient, however, has been 

 brought forward to show that every primary country displays 

 such an intimate bond of union between the granitic and 

 schistose groups, both in the small masses of granite entirely 

 contained in the slates, and in the main masses of these rocks, 

 that no line of demarcation can be said to exist in nature 

 between them, as laid down by our artificial systems. 



Before we proceed to the enquiry whether these groups 

 have been derived from distinct causes, operating at different 

 epochs, there are two other points to which we must briefly 



