40 SCIENCE PROGRESS 



we find four arcs, concave to the north and bending round to 

 the north-east, forming the nucleus, so to speak, of the Trans- 

 Himalayan series — viz., in succession from north to south, the 

 Terinam arc, the Lapchung-Shuru arc, the Kanchung-gangri arc 

 and the Lunpo-gangri — Chomo-uchong arc. 



It is to the western part of Dr. Sven Hedin's Trans- 

 Himalayan system that I wish to draw particular attention, for 

 in 1898^ I was able to discover a ver}^ similar mountain-entity 

 in the Taurus or southern border-range of the Armenian 

 plateau, which is merely a western member of the long chain 

 of plateaux stretching from Central Asia to the Mediterranean 

 Sea. The comparison in this paper between the Taurus and 

 the Trans-Himalaya will, it seems to me, throw some new light 

 upon the significance of the nature and position of the latter 

 with regard to the Tibetan plateau on the one hand and to 

 the Himalaya on the other hand. 



A glance at the sketch-map is in itself sufficient to show 

 how abruptly the parallel N.N.W. — S.S.E. ranges of the Trans- 

 Himalayan block abut against the east-west lines (with slightly 

 undulating crest-lines) of the Tibetan plateau; it is obvious 

 that these ranges must have been truncated on the north by 

 an east-west fracture coinciding with the great depression 

 marked by the chain of lakes already mentioned, and that on 

 the south they have been similarly truncated by a nearly parallel 

 fracture (W.N.W. — E.S.E.). The altitude of this system of moun- 

 tain ranges, consisting of green schists and grey granite, rises 

 steadily from 15,577 ft., the level of Lake Ngang-tsing at their 

 northern foot, to over 23,000 ft. at their southern termination, 

 where they are broken off no less abruptly, so that their ends 

 form a continuous but serrated wall facing the broad valley of 

 the Upper Brahmaputra and rising to form a watershed 8,000 ft. 

 above the river. All the rivers which rise from the lofty 

 snow-covered edge of this inclined block flow to the north-west, 

 in "consequent" courses down to the plain of depression, dotted 

 with lakes, at the northern foot of the Trans-Himalaya. It is 

 evidently the truncated edge of these serried ranges which has 

 given rise to the conception of an east-west range running 

 parallel to the Brahmaputra : it has indeed been laid down by 



' A Treatise on the Geology of Armenia., p. no : Beeston, Notts, 1906 ; and 

 my Geological Map 0/ Ar/nenia^ with explanatory pamphlet, pp. 5, 6 : Nottingham, 

 1906. 



