228 
Records of the Geological Suneg of India. 
[voL, xni, 
what could have produced straight, but not parallel, scratches on a hard corne¬ 
ous quartzite, I cannot say. They may bo glacial, hut their varying direction 
makes this very doubtful. 
To I’evert now to my own observations during the past season. I may commence 
by saying that a re-examination of the ground near Jand failed to verify the 
occurrence of ‘ erratic ’ blocks in the peculiar silt of that neighbourhood. The 
occurrence of ‘erratic’ blocks in this silt rests on two presumed instances-recorded 
in my paper (Records X, p, 142) of such blocks being seen reposing in sit.u 
and partly embedded in the silt; but from the conditions of the case, such 
an observation requires corroboration, and hitherto my search for a section dis¬ 
playing such blocks embedded in the silt has not been rewarded with success; and 
the glacial character of the deposit may therefore be still considered as unsettled. 
That this silt is a lacustrine deposit, is, I think, more than probable, and that it is 
really the homologue of the coarse alluvial accumulations near Rawalpindi, when 
the lower part of the Sohiin valley and the adjoining region along the Indus, 
with the Ohuch Hazara plain, constituted a lake through which the Indus flowed, 
and which owed its origin in part perhaps to that subsidence of the whole area to 
which the thick alluvial deposits in the Indus valley and its tributai’ies bear tes¬ 
timony. If my .suggestion is correct, that this silt is the exact homologue of the 
clays and gravels to the east and north, it at once explains why no erratics are 
found embedded in it, though more or less widely dispersed over the area covered 
by it, .since I shall presently show that the glacial conditions whereby the erratics 
in question became distributed, supervened on (that is, after) the deposition of 
the gravels in question. At page 51G of the Manual, Mr. Blanford suggests the 
idea of lacustrine conditions as contributing to the di.spei’sal of these blocks, with 
the altemative suggestion of a “ variation in the cowsa of tii-e Indies, and to the re¬ 
versed flow of its tributaries in great floods.'^ I shall endeavour to show that each 
of those sugge.stions has its share in pi’oducing the phenomena under review. 
The lineal arrangement of these ‘ eri’atics ’ in the Potwar,—one line following 
the general direction of the Sohan valley, whilst a parallel train of ereatics passed 
near Jand (Reo. X., page 142), could only have originated in two ways,—either 
through ‘ moraines ’ descending to the Indus trough, or through floating masses of 
ice sweeping up the tributary valleys during a reversed flow of the streams pro¬ 
duced by floods. And the result would not be interfered with, supposing the area 
adjoining the river to have been temporarily covered by a lake, as the reversed 
flow of the streams falling into the lake, during the rise in its waters resulting from 
Indus floods, would suSico to establish a direct current, mainly coinciding with 
the old river channels, through the body of still water of the lake at large and 
constituting water lanes, along which the eiTatic blocks and floating ice could 
bo carried, and to which the linear arrangement of the blocks now seen would 
be due. If, however, there was no lake, the ‘ reversed ’ flow of flood would pro¬ 
duce this lineal ari’angement of erratics, as a matter of course; but the presence 
of a lake would, I think, no less permit of a similar distribution of the blocks, and 
would fully account for their presence in the situations they are found to occuj^y, 
that is, on the top of the alluvium, as near Pindigheb, for example, and Taman. 
