

GEOLOGY OP THE T7PPEE PUNJAB. 365 



coaly or black alum-shales with inconstant bands of haematite are 

 found, generally near the base of the group, but with some excep- 

 tions. In the eastern half of the range the coal-shales, containing 

 one or a divided bed of coal three feet or less in thickness, lie very 

 near the base of the group ; further west there is nearly as much 

 Nummulitic limestone below as there is above them ; while south of 

 Sakesar Peak and near Kalabag the alum shales among the lower 

 beds occur on two or three horizons. This irregularity along the 

 southern base of the Eocene deposits, and the fact of their entire 

 absence at places about the east end of the Salt Range, as well as 

 in some localities trans-Indus, coincides with the local character of 

 the whole of these Nummulitic deposits. 



The smaller developments of limestone in the trans-Indus Salt 

 region and along the northern margin of the Rawal-Pindi plateau 

 approximate in general character and in abundance of organisms. 

 In the former region exceptional conditions must have prevailed to 

 have produced the great saline and gypseous group of that district ; 

 but there is as little to show what these were as there is in the case 

 of the Salt-Range saline series. 



The Eocene (?) trans-Indus salt is of a different colour from that of 

 the Salt Range ; it is uniformly grey, rarely so massive, often showing 

 its stratification more strongly, owing to numerous partings of 

 greenish clay between the beds, and much more frequently presents 

 a blotched appearance from the occurrence of pure crystalline 

 lumps in a more earthy or crypto-crystalline matrix. It shows at 

 Bahadur Kheyl an apparent thickness of from 1000 to 1230 feet, more 

 than double that of all the salt-beds at the Mayo mines in the Salt 

 Range, or more than equal to the whole salt-marl, salt, and gypsum 

 as exposed at the latter locality. In other places the thickness as 

 seen is not nearly so great, but nothing below the salt, is anywhere 

 exposed. The gypsum in this case also overlies the salt ; petroleum 

 impregnates both, and there are no volcanic rocks in association to 

 suggest any means of accounting for the peculiarities of the conditions 

 under which the salt and gypsum were accumulated. As to dis- 

 turbance, these beds have yielded to force quite in the same way 

 as any other stratified rocks. It is not easy to give a close estimate 

 of quantity from the varied nature of the exposures ; but a rough 

 one has been attempted, and on the supposition that the areas in 

 which salt is pretty certain to occur would together make up five 

 square miles, with an average thickness of only 200 feet, the amount 

 of salt present would be over 1500 millions of tons, sufficient, after 

 making a large allowance for waste*, to last at the present rate of 

 consumption for over 40,000 years. 



The Nummulitic zone bordering the northern hills, in its mixture 

 of limestones, clays, and sandstones, has more the character of an 

 offshore deposit than any of the apparently older and more exclu- 



* On exposed surfaces this salt is, of course, very liable to waste from solu- 

 tion. It is roughly estimated that 450,000 cubic feet are annually dissolved 

 and removed in this way. Mem. Trans-Indus Salt Region, cited above, Ap- 

 pendix, p. 221. 



