1875.] W. T. Blanrord— Flmi Cores and Flakes from Sind. 135 



The most remarkable point about the cores found by Lieut. Twemlow 

 Was that they were stated to have been obtained three feet below the rock in 

 the bed of the river. In a subsequent letter, (Geol. Mag. 1867* p. 43,) Gene- 

 ral Twemlow gave a section of the locality and explained that the specimens 

 sent were from " a mass of flints, packed together, in layers of from one and 

 and a half to two feet in thickness," resting on limestone which proved to 

 be true nummulitic limestone, full of JSl. lavigata, and covered by a recent 

 silt deposit. Although this' renders the matter rather simpler, because the 

 cores were found above and not beneath the limestone, still the circumstan- 

 ce of their being found in the mass of flints is not clear. I may add that 

 after examining the spot I have found the flints to be in place in the lime- 

 stone, in which they occur as nodules, often of very large size, and forming 

 in some cases imperfect and irregular bands in the strata, just as they do in 

 the chalk of England. 



I had occasion to visit Sakhar in the month of April last, and I natu- 

 rally made enquiries about the cores occurring there. I then learned, chiefly 

 from Mr. John Tate, C. E., that cores had been recently found both in the 

 Indus Channel and on the hills around Rohri. 



For the three cores now exhibited I am indebted to Mr. Tate, who 

 was in charge of some rock excavations for the purpose of preventing the 

 accumulation of silt at the mouth of the Sakhar canal. For this purpose 

 a channel had to be cut in the limestone of which the river bank is com- 

 posed at Sakhar, and in this limestone I am assured that the cores were 

 found ; and that in one case, at least, one was picked up immediately after 

 some rock had been blasted, at a depth of at least two or three feet from the 

 original surface of the limestone. 



The rock, as already mentioned, is nummulitic limestone and unmis- 

 takeably of Eocene age. But an examination of this limestone shews 

 that it is intersected in every direction by holes and crevices, many of 

 them of considerable size, and there can, I think, be very little doubt 

 that the cores have been derived from these crevices, which are usually 

 filled with a mixture of gypsum and clay. Whether the worked 

 flints have fallen into the crevices, or been washed in by the river, it is 

 impossible to say ; the cracks in question are for the most part horizontal 

 or nearly so, but the cores are in no case that I have seen rounded, as if 

 they had been transported for any distance by river action. 



There can be very little doubt about the late age of these cores. They 

 are by far the most carefully formed of any hitherto found in India, and 

 are so far superior to all ordinary forms made of the same material, that, as 

 was pointed out by Mr. Evans in the Geological Magazine, they rather 

 resemble those of Obsidian which are found in Mexico and in some other 

 places. The material of which they are formed is doubtless the flint which 



