INTRODUCTION. 3 



although the age of the salt cannot be closely fixed for want of certainty 

 as to the underlying strata, there is much to be recorded indicating that 

 it is contemporaneous with the basal portion of the ' Subathu' nummu- 

 litic series, and thus separated by many intervening geological periods 

 from the ancient silurian or pre-silurian salt of the Salt Range. 



The obscurity in which the origin of rock-salt masses is involved 

 appears to have been felt by our most distinguished geological authors, 

 and to have given rise to much diversity of opinion and theory as to the 

 natural conditions conducive to the formation of this mineral. This is 

 the more embarrassing, since it is one neither so rare nor so limited, as to 

 exposure, that some satisfactory conclusions on the subject of its forma- 

 tion might not have been expected to result from the development of, 

 geological science. As to quantity, one German author (Karsten) places 

 it after sulphur among the principal minerals formed in the crust of 

 the earth, and other distinguished geologists (S terry Hunt and David 

 Forbes)' 3 *' assign to it and its components a prominent place in the 

 chemistry of the primeval world. 



In the Kohat district occur what may be ranked among the largest 

 exposures of rock-salt known to exist upon the globe, and while engaged 

 upon the geology of such a region, attention was often attracted to the 

 probable past, as well as the actual present, physical relations of the 

 saline deposits. The record of the latter may throw no additional light 

 upon the origin of the local salt-rock, for its general characteristics seem 

 to be much the same as those of other salt deposits, if the size and 

 purity of the great accumulations here be excepted. But the collection 

 of observations is a necessary preliminary to accessions of knowledge 

 upon obscure points, while it also affords the only test by which the 

 correctness of conclusions can be tried. 



Before proceeding, cordial acknowledgments are due for liberal 

 assistance promptly rendered by Captain Cavagnari, Deputy Commis- 



* Geological Magazine, Vol. IV, pp. 357 and 433, &c. 



( 107 ) 



