The Gneissose- Granite of the Himalayas. 305 



The first point is the age to be assigned to the intrusion of the 

 gneissose-granite. 



Mr. Middlemiss discusses, among other things, the origin of 

 the granite: namely, whether it was an ancient gneiss (p. 273); 

 a metamorphosed sedimentary rock (p. 275) ; or a true granite. 

 I do not propose to go into these questions, because Mr. Middlemiss 

 freely admits that, whatever its origin and mode of birth may 

 have been, it behaved as a granite* when it intruded into the 

 Himalayan strata. If a rock be mineralogically and functionally 

 a granite, I am not disposed to make curious inquiries of Vulcan as 

 to whether it has a bar sinister on its escutcheon. If it behaves 

 like a granite and a gentleman after its introduction into polite 

 geological society, I am satisfied. 



It is not alleged that the foliation to be observed in the granite 

 is due to the original taint in its birth ; on the contrary, another 

 and post-genital cause is assigned. This discussion as to its origin 

 is therefore, as far as the geology of the Himalayas is concerned, 

 a purely academic one. Mr. Middlemiss holds that the granite — 



1. " Must have been so heated as to get at least into a plastic 

 state in which it was capable of considerable movement under 

 pressure along lines of least resistance " (p. 273) ; and was capable of 

 " in part consuming " the strata into which it was intruded (p. 274). 



2. That it functionally acted as an igneous intrusive rock 

 (pp. 274, 276). 



3. That it sent off dykes, sills, and intrusive veins into the 

 adjoining rocks — instance, figs. 1, 2, 4, 44, 45, 51, and 52, and 

 l^p. 61, 63, and 64. 



4. That it is " always surrounded by a concentric zone of well- 

 defined extra metamorphism " (p. 276). 



5. That it contains numbers of " included fragments of schists 

 and quartzite " (p. 63). 



As the gneissose-granite was intruded into the Himalayan strata 

 long subsequent to their deposition, and as it uniformly behaved 

 as an igneous rock, I think we may content ourselves with calling 

 it a granite and pass on to consider the actual date of its intrusion. 

 Mr. Middlemiss considers that its age " must be at least Pre- 

 Triassic, whilst it is possible that it may be earlier than Carboniferous, 

 e.g. Silurian" (p. 278). The reasons which the author assigns for 

 this opinion, briefly stated, are as follows : — 



1. The absence of metamorphism in Tertiary beds (p. 137) ; and 

 the non-occurrence of granite in Tertiary strata (p. 277, footnote). 



2. The occurrence of Murree beds and Numraulitic limestone in 

 direct and normal superposition immediately above thin-bedded 

 rocks exhibiting distinct metamorphism (p. 135). 



3. (a) The non-occurrence of intrusive granite in the " Tanols." 

 (6) The opinion of the author that the granite is older than 



the " Tanols." 

 (c) The probability that the " Tanols " derived their materials 

 from the granite. 



(a) (&) (c) will be found at p. 239 (6). 



DECADB IT. — ^TOL. IV. — NO. Til. 20 



