67 
PAUT 1.] Ljjdekher •. Geology of Laddk and NeighboHring Bistrlds. 
The slates of Lama-Yuru, Tankse, the Pangong Lake, and the Chang-Chenmo 
valley, from their similarity in mineral composition to those of the Dras river 
are likewise inferred to he of the same age, which inference is strengthened hy 
the slates of Pangong, which can he traced into connection with those of Tankse, 
underlying strata of presumed Carboniferous age. 
The slates and gneiss of Rupsu, which likewise underlie Carboniferous strata, 
must also be placed on the same horizon. 
6. The lower gneiss. —In the foregoing sketch it has been shown that the 
gneiss of the Kailas range conformably underlies a large thickness of slates, 
which seem to correspond approximately in position to the Silurian : following 
the same system of nomenclature, such gneiss may be termed Cambrian gneiss 
as consisting of a distinct geological formation. It has further been shown on a 
previous occasion,' that the gneiss of the Zanskar range and of Kashmir is simi¬ 
larly sitvrated in regard to the slates of those districts, which are also classed as 
Silurian ; there is, therefore, considerable primd facie evidence that all this gneiss 
is contemporaneous. 
It now remains to consider whether any or all of such gneiss is equivalent to 
the “central” gneiss of Dr. Stoliczka. It aj)pears from the sections of the gneiss 
and Silurians in the Spiti district, where the “ central gneiss” was first named, 
that that gneiss is unconformable to the Bhabeh Silurians, though this is not 
clearly stated in the text: if this be true, the central gneiss existed as such at the 
time of deposition of the slates Dr. Stoliczka, however, himself recognised the 
gneiss of North Lahul as “central gneiss,”" and also suggested that some of the 
gneiss of the Zanskar range to the south of Padam and Sum belonged to the 
same formation. No evidence of unconformity can be seen in this section. 
It has been noticed in my paper on the gneiss of the Zanskar range" that 
possibly some portion of the latter was gneiss at the time of the deposition of the 
Silurians; and it was suggested that such gneiss might bo the equivalent of the 
“ central gneiss.” It was also shown on that hypothesis that the gneiss in North 
Lahiil identified by Dr. Stoliczka as “ central gneiss,” must, if rightly identified, 
be unconformable to the overlying Silurians. But until the conformity or uncon¬ 
formity of the central gneiss is elsewhere settled, it cannot bo settled here. 
It, therefore, seems pretty clear that the “ central ” gneiss is represented in 
the ZanskSr range, but, as I have said in my above quoted paper, how much or 
how little of such gneiss is “ central gneiss ” cannot be determined. Similarly, 
in the Kailas range, it is probable, in my opinion, that the lower massive gneiss 
may be the central gneiss, and therefore unconformable to the higher gneiss 
beds, if the central gneiss is always so: how much or how little of the conti’al 
gneiss occurs there I cannot possibly say. As in my other maps, the whole of 
the gneiss underlying the Silurian slate series has been colored the same tint, and 
has been called central gneiss; this gneiss must, however, include both the gneiss 
conformable and that unconformable to the slates (if there be such) and migh t 
rather have been called Cambrian and central gneiss. 
’ Eec. Geol. Surv. India, Vol. XI, p. 59. 
^ Mem. Geol. Surv. India, Vol. V, p. 341. llec. Geol. Surv. India, Vol. XI, p. 59, 
* Kec. Geol. Surv. India, Vol. XI, p. 60. 
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