1842.] of the Himmalay a Mountains. cxliii 



I have seen, certainly is in contact with a rock forming a transition be- 

 tween granite and gneiss. With regard to the beds, they also present in 

 general the appearance of a thin band of gneiss surrounding them, and 

 outside of this is found mica slate. The whole being included in clay 

 slate, no change in the latter rock has even been observed. It is al- 

 most unnecessary to say that none of these beds are stratified,* that is, 

 the central nucleus ; but as before stated, they appear to pass into gneiss 

 on their boundary. The only imbedded minerals are schorl and quartz, 

 (rhombohedral schorl and rhombohedral quartz.) 



303. Conterminous with the gneiss may be found a series of dif- 

 ferent rocks all possessing the schistose structure, micaceous, chloritic, 

 and talcose schists ; whether all to be included under one head, is a point 

 for the determination of which data are as yet wanting. But it is per- 

 fectly certain, that there is no such thing as a general and continuous 

 formation of micaceous schist (the next rock in our systems) analogous 

 to that of gneiss ; several large patches of micaceous schist occur, but 

 they are separated by equally large tracts of other schists. Perhaps 

 the above three schists might be conveniently considered as one forma- 

 tion, although we should even then find our systematic views disturbed 

 by the intrusion of schists of an argillaceous character. These latter 

 may be seen even in contact with the gneiss. Thus we shall be forced 

 to modify a little our ideas of the exclusive nature of formations, and in 

 admitting argillaceous schist as a member of the series, we shall esta- 

 blish, as succeeding the gneiss, a zone of schistose rocks of nearly equal 

 extent, but not presenting the same appearances of regularity of position, 

 or uniformity of mineral composition. 



304. In considering the subject, I have been certainly inclined to 

 view this latter account as most consonant with the phenomena. But 

 it is possible that a more particular examination of the boundary of the 

 gneiss may establish the first view, and in this case, the gneiss with 

 which the argillaceous schist is in contact, would belong to a different 

 era from that of the zones of greatest elevation, whereas I have suppos- 



* The stratification of granite, a favourite tenet of one of the rival schools of geology- 

 appears to be losing ground every day. Mr. Greenough long ago, in his critical 

 examination, shewed the extreme laxity with which this term stratification had been 

 used. In the sense in which most unlearned people understand it, I apprehend that 

 granite can never be said to be stratified. After all, however, it is a mere dispute about 

 words, and seems, whichever way determined, to throw no light on the subject of the 

 origin of rocks. 



