296 Rev. Br. Irving — On Dynamic Metamorphism. 



independent evidence in favour of the view that the elevation of 

 the Thibetan plateau is of post-Siwalik date ; for remains of 

 Bhinnceros and other large mammals occur at an elevation of 15,000 

 feet in Thibet, and it is not probable that these animals lived in so 

 elevated a region " (id. pp. 585 and 586). 



Here is assuredly an important w^itness in support of the views 

 of Falconer and of Strachey, behind whose broad segis I claim to 

 stand. 



In conclusion, there are two statements in Mr. Blanford's 

 communication which I wish to traverse. He says Mr. Lydekker 

 is of opinion that the Ehinoceros remains from the Hioondes 

 plateau are of Pliocene age. Mr. Lydekker was once of that opinion, 

 but he subsequently withdrew it, and has printed his opinion that 

 he now holds the beds in which they occur to be of post-Tertiary age. 



In another venture Mr. Blanford says, "That if I had had an 

 opportunity of seeing what is perhaps the grandest example of 

 subaerial denudation in the world, I should be as little inclined as 

 he is to believe that such gigantic furrows as the Himalayan valleys 

 can have been ploughed out by rain and rivers since the frozen 

 Mammoths were imbedded in the Siberian tundras." 



My answer is that I do not for a moment believe that these 

 furrows were ploughed out by rain and rivers at all, and that it 

 seems to me as incredible to believe that the splintered precipitous 

 and sharp-edged precipices of the Himalayan valleys were carved 

 out by such agencies as that the Matterhorn or the pinnacles of 

 the Sierra Nevada or other similar objects were thus shaped. The 

 theory which attributes such forms to this kind of denuding agency 

 seems to me absolutely transcendental, and to involve a reductio ad 

 ahsurdiim of Uniformitarian Geology. 



V. — On Dynamic Metamorphism.^ 

 By the Eev. A. Irving, B.A. and D.Sc. (Loud), F.G.S. 



IN the originally epistolary form of my previous communication^ 

 on this subject brevity was aimed at as far as possible. It was 

 written at the time the letters therein referred to appeared, and my 

 object in throwing out such suggestions as I have ventured to make, 

 was to call the attention of writers on petrological subjects to the 

 desirability of avoiding a certain looseness of thought, which seemed 

 to attach itself not infrequently to the terms ' chemical change ' and 

 ' chemical action.' 



Mr. Fisher's letter^ in reply thereto is in reality an appeal from 

 the creed of the geologist, not to chemistry, but to the creed of the 

 chemist. I am certain it will satisfy no one who has made a real 

 study of chemical physics. 



The instances of the formation of CO and NO which have been 

 cited, along with a good many of the immense number of "parallel 



1 "Written in January last. 



2 See Geol. Mag. Dec. III. Vol. VII. pp. .562-564. 



3 See the letters of Mr. Fisher and Mr. Harker in the Geological Magazine 

 for January, 1891. 



