GEOLOGY. 5 



fined. This area has somewhat the form of an oblong, with the longer axis north-west and 

 south-east. Its north-eastern boundary is formed by the Indus, whilst the south-western bound- 

 ary is far less regular, and, bulging out near the southern corner, includes a considerable tract 

 of country about Spiti, Kulu, and Lahaul. The south-eastern limit of the area examined is 

 formed by a line drawn north-north-east from Simla to the Indus, the north-western extrem- 

 ity being near Kargil and Dras. The south-western boundary is formed first by the range 

 which separates the Kashmir valley from that of the Indus, and the continuation of the same 

 in the Zaskar range as far as the Baralatse or Baralacha pass, whence the boundary turns 

 southward and embraces the country between the Baralatse range and the snowy ridges north 

 of the Sutlej valley, near Simla. 1 



The general formation of the mountains near Simla is too irregular for any definite range 

 of great length to be distinguished. The ridges throughout the North- Western Himalayas 

 and Western Tibet have a general north-west and south-east direction, shown by the main 

 course of both the mountains and river valleys ; and this direction is, of course, due in a great 

 measure to the strike of the various rocks, and the outcrop of softer or harder strata. Com- 

 mencing at the south, 2 the range north of the Sutlej, opposite Simla, usually considered the true 

 Himalaya, and well known to all visitors to Simla as the snowy range, is chiefly composed of the 

 rock called by Dr. Stoliczka " central gneiss." 3 The mineralogical character by which this rock is 

 distinguished is the presence of albite in large quantities, with quartz, orthoclase, and biotite, 

 and a still more marked peculiarity in the constant occurrence of veins of albite granite, 

 which traverse the mass in every direction. 



To the south of the central gneiss various metamorphic rocks are found : to the north or 

 north-east of it commences the sedimentary area of Tibet. It is palpable that this central 

 gneiss is not only pre-silurian in age, but that it must, in all probability, have been metamor- 

 phosed before the deposition of the silurian strata. Hence its importance : for whilst other 

 metamorphic formations of the Himalayas and Tibet are, probably, represented by fossilif erous 

 sedimentary deposits in other parts of the range, the central gneiss appears to belong to an 

 older period altogether. 



To the north-west this gneissic formation extends but a short distance. The natural 

 continuation of the range formed by it would be the Pir Panjal, south-west of Kashmir ; but 

 this consists of newer formations. Dr. Stoliczka was inclined to consider the Zaskar ridge as 

 the probable continuation of the central axis, as he considered it, and to look upon the gneiss 

 of which that range consists as the representative of the central gneiss. It, however, wants 

 the albite granite. 



The highest peaks of the snowy Himalayan range consist of silurian rocks dipping 

 northward, and followed in ascending order by carboniferous, triassic, and Jurassic strata. 



1 For convenience sake, it maybe as well to point out that the principal ranges of the North-Western Himalaya and Western Tibet, 

 all running nearly north-west and south-east, are, commencing on the north, the Kuenluen range on the edge of the Yarkand plain ; 

 the Mastagh range traversed by the Karakoram pass, and forming the main ridge, separating the Indus watershed from that of the 

 Yarkand plain ; the Ladak range running along the northern (or north-eastern) bank of the Indus, and separating its valley from 

 that of the Shayok ; the Zaskar range, which forms the south-western limit of the Indus drainage, extending along the north-eastern 

 boundary of Kashmir, and the continuation of which to the south-west is sometimes known as the Baralatse range, and the Hima- 

 laya proper, the north-western continuation of which is the Pir Panjal. 



2 The account which follows is derived in great part from Mr. H. B. Medlicott's sketch of the Geology of the Panjab and its 

 dependencies in the Panjab Gazetteer. 



3 Some important additional information concerning this rock has recently been furnished by Colonel C. A. McMahon, who has 

 determined by microscopical examination that this gneiss possesses the characters of an igneous rock, in parts at all events, and that 

 it must probably have been in a more or less plastic or fluid state. Records, Geol. Surv. Ind., X, p. 222. 



b 



