42 SCIENCE PROGRESS 



and in the Karabagh and Karadagh blocks to the south ; in 

 all these cases, as in the Tauric block, the fault-scarp looks 

 down upon depressions partly filled with recent lake-deposits 

 and with lavas, which have welled up either from this fracture 

 or from fractures parallel to it. The fact that the rivers in each 

 case adopted "consequent" courses goes to show that the surface 

 of the blocks must have been planed down either to a plateau 

 of marine erosion or to a pene-plain prior to the uptilting. 



Now in Central Asia we find that the Kashgar ridge is always 

 mapped as a range running from N.N.W. to S.S.E. ; yet here again 

 it is merely a mountain wall, in which the ends of the Pamir 

 ranges (with a W.S. W. — E.N.E. direction) are suddenly broken off 

 by a great fault to face the deep Tarim depression (3,500-4,000 ft.) 

 in a lofty snow-capped escarpment rising to 25,800 ft. in the 

 peak of Mustagh-ata (see map). Although it is many years 

 since Fedchenko^ took this view of the so-called Kashgar 

 range, this brilliant generalisation, so far ahead of the time, has 

 hitherto escaped recognition, with the result that the structure 

 of this part of Central Asia has been rendered unnecessarily 

 obscure and complicated. It is noteworthy that (as is typically 

 the case with lines of fracture) hot springs occur along this line, 

 e.g. at Khajan-aksai (lat. -^f) in the valley of the Raskan Daria. 

 The Pamirs may in fact be regarded, broadly speaking, as an 

 uptilted block of previously folded strata, breaking off in an 

 abrupt fault-scarp on the north-east towards the deep Tarim 

 basin, whilst its surface, furrowed by "consequent" rivers, 

 slopes gently from this uptilted edge of the Kashgar mountain 

 wall down to the transverse valley of the Panj or upper Amu 

 Daria in the south-west, where there is no such border-ridge. 

 In this part of the Tian Shan system, as well as in the district of 

 the Ferghana depression, the N.E. — S.W. chains belong to an 

 older period of folding, whilst the N.W. — S.E. chains belong to 

 the more recent (Tertiary) period, to which the fractures in 

 the same direction, e.g. the Kashgar and Indus-Sutlej (Nari 

 Khorsum) faults also belong. The Darwas fracture or disloca- 

 tion, curving round from S.W. to S.S.W., to which Suess ^ and 

 Krafft^ have called attention, probably indicates (together with 



* Joiirn. Roy. Geogr. Soc.^ London, 1870, xl. 

 2 Antlitz der Erde, iii. (i), p. 2,77 and Taf. xiii. Vienna, 1901. 

 ^ "Geologische Ergebnisse einer Reise durch das Chanat Bokhara." Denkschr, 

 Akad, Wieji^ 1900, Ixx. pp. 49-72 and map. 



