84 Records of the Geological Survey of India. [vol. vii. 
was an isolated basaltic dyke seen, or tlie tertiary sandstone cropping out from under the more 
recent deposits. 
Viewing the country from an elevated position near our camp at Turug-at-bela, the 
conglomerate and gravel beds, well clad with grass vegetation, were seen to stretch far away 
eastwards, and in a north-easterly direction across the Turug pass ; while on the south they 
were bounded by a continuation of the somewhat higher basaltic hills. Towards the west 
I traced thorn for about seven miles, across a low pass at which a tributary of the Toyan 
rises in two branches; while on the other side two similar streams flow west by south to join 
the Suyok river. To the north the proximity of a rather precipitously rising range shut the 
rest of the world out of view. For this ridge the name Terek-tagh of Humboldt’s map may 
be retained; its average height ranges between about 16,000 and 17,000 feet. In its western 
extension it runs almost due east-west, composed at base of a tough limestone conglomerate 
of younger tertiary origin, followed by white dolomitic limestone, and then by a succession 
of slaty and dark limestone rocks, the former occasionally showing distinct signs of 
metamorphism, and changing into schist. All the beds are nearly vertical or very highly 
inclinod, dipping to north by west, the older apparently resting on the younger ones. 
North of Turug-at-bela the range makes a sudden bend in an almost northerly direction, 
and continues to the Chaderkul, where it forms the southern boundary of the lake-plateau. 
By this time the white dolomitic, and afterwards the slaty beds, had entirely disappeared, 
and with them the height has also diminished. A comparatively low and narrow branch of 
the range which we visited consists here entirely of dark limestone, which in single frag¬ 
ments is not distinguishable from the Trias limestone of the Koktan mountains, but here 
it does not contain any fossils. The ridge itself, after a short stretch in a north-east- 
by-north direction, gradually disappears under the much younger conglomeratic beds. 
Across tho Chaderkul plain the true Thian Shan range was visible, a regular forest of 
peaks seemingly of moderate and tolerably uniform elevation. The rocks all exhibited dark 
tints, but most of them, as well as the hills to the west of the Chaderkul, near the sources 
of the Arpa, were clad in snow. The lake itself was frozen, and the surrounding plain 
covered with a white sheet of saline efflorescence. 
Brief sketch of tlie geological history of the hill ranges traversed. —In order that the 
preceding remarks may be more easily understood, I add a few words regarding the changes 
which appear to have taken place at tho close of tho kainozoic epoch within the southern 
offshoots of the Thian Shan which we visited. 
Short as our sojourn in the mountains was, it proved to be very interesting and equally 
instructive. Humboldt’s account of the volcanicity of the Thian Shan, chiefly taken from 
Chinese sources, receives great support; but we must not speculate further beyond confiding 
in the expectation that both meso- and kaino-zoic rocks will be found amply represented 
in it. 
As far as our present researches in the physical aspect of the country extend, we may 
speak of three geologically different ranges: the Terek range, which is the northernmost, 
the Koktan in the middle, followed by tho Artush range, below which begins the Kashgar 
plain. All throe decrease in the same order in their absolute height, the last very much 
more so than tho middle one. The first consists of old sedimentary rocks, the second of 
similar rocks in its southern parts, while younger tertiary and basaltic rocks occupy the 
northern portions, tho third is entirely composed of young tertiary deposits. The general 
direction of all the ranges is from west to east, or nearly so; this direction evidently dating 
from the time when the whole of the Thian Shan chain was elevated. The undulating high 
plateau between the Terek and the Koktan is, near Turug-at-bela, about eight miles wide, the 
