3'54 C. A. McMaJion — Gneissose- Granite of the Himalayas. 



the tangential pressure which crumpled up the strata produced 

 foliation in the schists and granite, how did the dolerite escape 

 uninjured? This is the more remarkable as dolerite takes on 

 foliation very readily. The author has not given any explanation 

 of the difficulty. 



Mr. Middlemiss appears to rely very much on shearing and 

 molecular movement to account for the results which he attributes 

 to dynamo-metamorphism. "If we believe," the author writes, 

 " (as we have a right to do from considerations as to the deep- 

 seated nature of granite) that very great thicknesses of the slate 

 or schistose rocks once overspread that ci"ystalline core, we can 

 understand that lateral stresses, if sufficiently powerful and long- 

 continued, acting on such a material would be unable to violently 

 fold and plicate them on a lai'ge scale, but would spend themselves 

 in minute deformation of the rocks in shearing and in other ways 

 characteristic of dynamic metaraorphism " (p. 280). 



If shearing and molecular movement took place in Mr. 

 Middlemiss's crystalline and metamorphic zone to the extent 

 supposed by the author, great heat must have been generated, 

 and strong chemical action must have resulted. It is curious, 

 therefore, to notice that these much " mashed " rocks, to use a term 

 employed by geologists over the Atlantic, do not appear to have 

 yielded the author much in the way of dynamo-metamorphic 

 minerals. One reads of mica and of " incipient garnets," " which 

 occur as minute specks or raised blisters " (p. 55), but I cannot call 

 to mind anything else. This poverty of chemical and mineralogical 

 result after the expenditure of so much dynamic energy recalls an 

 ancient proverb to the effect that " a great mountain was in labour 

 and brought forth a small mouse." ^ 



I see no reason to believe that the great masses of gneissose- 

 granite now to be seen in the Himalayas were " mashed " by 

 jDressure after cooling and solidification. In following outcrops 

 along the line of strike, as for instance along the Shankan outcrop 

 in the Simla regions (Eecords G.S.I., x, p. 217), the granite passes 

 repeatedly from massive to foliated, and from foliated to massive, in 

 an apparently capricious manner. This feature I think quite in- 

 compatible with the supposition that the foliation is the result of 

 shearing subsequent to the solidification of the rock, either in the 

 direction of the strike or in the direction of the dip. 



I would again invite attention to the heliogravure of an inclusion 

 in the Dalhousie gneissose-granite published at p, 174, in vol. xvii, 

 Records G.S.I. The plate represents a cross-section of a splinter of 

 schist two feet long, shaped like a tent-peg. The outlines of the 

 inclusion are perfectly sharp, and it is evident that the granite in the 

 locality where the inclusion was found cannot have been sheared 

 after the inclusion of the fragment. Had shearing taken place the 

 inclusion would have been flattened and drawn out into ribbons. 



To sum up, I think that though the facts brought before us in 

 Mr, Middlemiss's Memoir are interesting, they shed no new light 

 1 " Farturiunt montcs, nascetur ridiculus urns.'" — Horace. 



