42 WYNNE: TRANS-INDUS SALT REGION, KOHAT DISTRICT. 



Anything worthy of the name of an inland sea or large lake would 

 cover the whole of the salt-bearing country, as far as extent goes, and as 

 the gypsum extends much beyond the salt region, while all the rocks of 

 the district may once have had an expansion one-third greater in a 

 north and south direction, it is probable that the saline water would 

 have occupied or exceeded the largest area named. 



This rough estimate will serve to show that, according to existing 

 natural conditions, there is sufficient salt in a rocky form in this district 

 to have impregnated all the waters of a considerable sized inland lake 

 or sea. The mode of its collection into the form of solid strata of large 

 thickness and greater or less horizontal extent, or the conditions under 

 which the water would have disappeared by evaporation, conformably 

 with what appears to be the most generally adopted theory, can only be 

 surmised. 



In the last paragraphs sea- water has been used to illustrate the 

 probable formation of the salt, its composition being better known than 

 that of the waters of many inland lakes or seas, which might give 

 different results, but from a passage in Dr. T. S terry Hunt's lecture 

 on the chemistry of the primeval earth (Geological Magazine, Vol. IV, 

 p. 364), he would seem to believe that " there has been a slow progressive 

 change in the constitution of the ocean," so that the conditions may not 

 now remain the same as they were when the salt was deposited. 



Assuming these to have been at least similar to some extent, what 

 special causes there may have been in operation to facilitate the forma- 

 tion of the rock-salt there is little or nothing to suggest. In this 

 connexion it may be observed that the circumstances of deposition 



generally in the Upper Punjab seem from very early palseontolo- 



i. 

 gical times to have been subjected to strange peculiarities of lateral 



limitation. The thinning out of whole formations may only mark 



absence of material to be deposited ; in the case of sedimentary rocks, 



but in those of chemical origin, the depositing seas would themselves 



appear to have been limited or divided by land. Together with the 



( 1*6 ; 



