I to 
HAYDEN: GEOLOGY OF SPITI. 
frequently full of large; concretions, and no pebble or boulder-bearing 
bed has been found with a silty matrix. There is therefore no evi- 
dence in support of the theory of a glacial origin for the conglomerates, 
which, with the slates, grits and quartzites with which they are 
associated, are just such rocks as might be expected to occur among a 
series of shallow-water deposits laid down in estuaries or in the 
neighbourhood of a shore-line. 
Figure 3, Plate XVII, represents the matrix of the Blaini boulder- 
slate as seen on the Mall at Simla, near Sanjauli bazar. It will be seen 
that it is very much finer than the matrix of the Spiti conglomerate, 
while the present writer "has found that larger boulders occur in the 
Simla rock than are to be seen in its supposed representatives in Spiti. 
It would seem, therefore, that correlation of the two series on the ' 
ground of a common glacial origin is not warranted, but this cannot be 
regarded as sufficient reason for denying that such correlation may 
still be correct. 
Certain other points of resemblance were found by Mr. Oldham 
between the Blaini rocks and the permian beds of Spiti; one of these 
was the occurrence of carbonaceous shales above the boulder-bearing 
beds in both areas. The carbonaceous shales of Simla require little 
description : they are soft, densely black and graphitic, their appear- 
ance having frequently led to their being mistaken, by those not versed 
in such matters, for coal. On the other hand, their supposed repre- 
sentatives in Spiti, which have been described in this memoir as the 
" Productus shales," though certainly black at times, are more usually 
dark-brown, gritty and micaceous, with a few indistinct plant impres- 
sions in the lower beds. They have not, however, even where greatly 
metamorphosed, as in Rupshu, that intensely black, coaly and graphi- 
tic appearance so characteristic of the Simla carbonaceous shales, 
which are much more nearly related, lithologically, to the cambrian 
carbonaceous shales of Bashahr. 
i; A further argument adduced by Mr. Oldham in favour of his 
correlation was the common resemblance of the Po conglomerate and 
the Blaini boulder-slate to the Panjal conglomerates of Kashmir and 
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