DESCRIPTIVE GEOLOGY: GENERAL CONSIDERATIONS. 273 



Without compromising ourselves, therefore, by making any state- 

 Concluding remarks ments as to the a S e of the upheaval and build- 

 under this head. j n g f the Himalaya— as no two writers can 



agree as to the right limitation of the terms, seeing that, day by day, age 

 by age, and period by period, it expands in one direction and diminishes 

 in another — we may I think consider it as proved that different parts 

 of that range in the form of longitudinal strips or blocks of strata, 

 have had different histories, and played different parts in the evolution 

 of the mountain-range as we see it now ; and that on the whole, the 

 southern aspect of the range has been fashioned, not all at once, but 

 piece by piece ; so that, like a house that has been added to at differ- 

 ent dates, it shows by signs of age, by variety in the style, and by a 

 change in the building material, the different stages through which it 

 has passed before becoming the still-unfinished edifice of to-day. 

 In taking account of any general theory - of the Himalayan 

 _, _,. mountains or their western continuation in 



The great crystalline 



granitic or gneissicaxis Hazara, there is one great factor that cannot 

 of the Himalaya. . 



be overlooked, one indeed to which our atten- 

 tion 'naturally turns when contemplating them, namely, the great 

 crystalline core which forms the line of the central snowy peaks. 

 About the exact nature of this crystalline core there are opposite views. 

 Some observers regard it as an ancient gneiss, at least in great 

 part; whilst some believe it to be, at least largely, a foliated granite. 

 I do not propose to argue out a question of this kind, which indeed 

 in these days seems to be a gratuitous undertaking, inasmuch as 

 in certain ultimate stages of both rocks modern opinion seems to be 

 inclining to the view that they may not only be structurally consti- 

 tuted alike, but, within limits, functionally act alike. 1 



So far as Hazara and such parts of the higher and lower Himalaya 

 that I have seen are concerned, the rock if originally a gneiss, must 

 have been so heated up as to get at least into a plastic state in which 

 it was capable of considerable movement under pressure along lines 



1 See papers by Dr. A. Lawson, Ann. Rept. Canadian Survey 1887, p. 33, and by G. 

 Barrow, " On an intrusion of a Muscovite -biotite gneiss in the S. E. Highland of 

 Scotland" Quart. Journ. Geol. Sec. Lond. Vol. XL1X, p. 330, Aug. 1893. 



T ( m ) 



