1>AKT 1 .] LydeJcker : Geology of Ladak and Neig/iljouring Bintricts. 
31 
to tlio south-east. To the uorth-west of Tankse, the fault, on the other hand, 
seems to have died out, and the slates appear to rest conformably in a regular syn¬ 
clinal of the gneiss. Taking a transverse section to the south-west from Tankse 
vidiVo Kai Ld, we find to the east of Kiii Tso the slate series with a north-easterly 
dip, underlaid conformably by the white non-porfihyritic gneiss of the Indus 
valley. This gneiss, especially in its higher beds, contains not unfrequently bands 
of a darker color, as we found to be the case at Tankse. 
Some of the slates, in the middle of the series, between Tankse and the Kai 
La have been locally altered into a fine-grained, dark-colored, and generally 
imperfectly crystallized gneiss, quite distinct in character from the underlying 
white gneiss. Further to the north-west on the road between Tankse and 
the Chang Ld, the upper dark gneiss, altered out of the slates, is seen 
resting on and passing down into the white gneiss of Tankse. This section, 
therefore, establishes the important fact that there exists in Laddk gneiss of 
two distinct ages...one altered out of Silurian slates, and another underlying 
such slates, but apparently also, at all events partly, altered out of an older con¬ 
formable series. This fact may lead, as mentioned, to the inference that the 
darker colored and higher gneiss of Kargil, already referred to, may really 
very possibly bo the altered Silurians, though, as before said, the question 
cannot at present be definitely settled. 
As already stated, the white gneiss of the Indus valley dips generally to the 
north-east, and the higher beds consequently form the summit of the Kailas 
range. Along the greater part of the Indus valley in Ladak the white gneiss 
continues to the crest of the range, but near Leh itself, below the Khardong La' 
and Laswan Ld, wo find the white syenitic gneiss [overlaid by alternating bands 
of dark and light-colored gneiss like the higher gneiss of Tankse and the Kai 
Ld. This striped gneiss is again succeeded by an imperfectly crystalline, dark- 
colored, and fine-grained gneiss, alternating with partially altered slaty rocks, 
and occasional unaltered slates. These rocks appear to occujiy a sj-nclinal ellip.so 
in the white gneiss, the boundaries of which are approximately indicated on the 
map. From the nature and position of these rocks, I have little doubt but that 
they are the altered equivalents of the slates to the south of Tankse, and they 
have been colored accordingly in the map ; this is, however, only a conjectural 
coiTclation. 
To the northward of Leh, the crystalline series has been traced by Dr. Bellow 
along the Shahidula and Yarkand road as far as Sa-Sango where it appears to 
bo succeeded by Silurian slates. 
Returning once again to the Tdnkso district, wo find that the range to the 
south-east of Tankse, running parallel to the north-western half of the Pan¬ 
gong lake, consists of the porphyritic gneiss of Tankse. This gneiss I 
have traced some distance to the south-east of Shushdl, where it is overlaid by 
Silurian slates, connecting those to the south of Tankse with those of the Pan¬ 
gong lake, which will be referred to immediately. On the northern flank of the 
' This pnss is callctl on the Topographical Survey maps the Laou'chi Ld, though it is always 
spoken of by the natives as the Khdrdong L&, 
