ECONOMIC ASPECT OF SALT REGION. '221 



whole of the above area as only 200 feet, this would give an amount 

 of 40 milliards of maunds, sufficient, after making a large allowance for 

 waste, to last at the present rate of consumption for over 40,000 years. 



With such a vast supply there is little necessity to speculate, for 

 practical purposes, about the existence of further salt treasures below 

 the great gypsum area of these hills, but it would be satisfactory, in a 

 scientific point of view, to know whether the salt is, or is not, as continuous 

 as the gypsum under which it lies.* 



Waste of the salt by rain and in quarrying. — The average rainfall 

 registered at Kohat Station between 1863 and 1873 was 17*12 inches, 

 and at Banmi 11*25 inches, averaging 14*19 inches. If we suppose 

 the latter amount of rain to fall annually upon the exposed salt surface, 

 and a saturated brine to result, 0*2 feet of salt will be dissolved 

 annually, but taking only 0*15 feet instead, as the brine would not be 

 quite concentrated, the conclusion is arrived at that 4 J lakhs of cubic 

 feet of salt are annually dissolved and carried off by rain water from 

 exposed surfaces, an amount equal to 742,500 maunds of rock-salt ! 



Much salt must also be carried away by subterranean percolation 

 of rain water, as may be seen in the incrustations of numerous brine 

 springs, so that it will be within the limits of probability to say that 

 the annual waste by natural agencies is equal to twice the amount sold. 

 Compared with this great source of loss, the waste now taking place 

 at the quarries by throwing away the small salt seems insignificant, 

 being, perhaps, annually not more than one-sixth of the amount removed 

 from outcropping salt by rain. 



* This question applies both to the Cis-Indus and Trans- Indus salt regions. In both 

 the gypsum extends through the hills, but the salt may be supposed with much probability 

 to have a lenticular disposition. Here and there it reaches an enormous thickness, appa- 

 rently over 1,000 feet in this region, and up to 600 feet in the other, but in other places it 

 may have altogether disappeared. 



The theoretical supposition of the salt having been deposited from the evaporation of 

 sea water, separated entirely or temporarily from the ocean, and thus collected in the deeper 

 pools or hollows, will be found mentioned above. 



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