262 Report on the Geological Structure of the Salt Range. [No. 3. 



accounted for, by supposing that the mineral acid in union with 

 which the magnesia has been introduced, has in accordance with the 

 known laws of chemical attraction, combined with the calcareous 

 matter of the fossils, and caused their disappearance. A similar 

 theory to account for local deposits of gypsum in the midst of calca- 

 reous strata has also been propounded, viz. that vapours of sulphuric 

 acid generated during the prevalence of igneous action, have been 

 injected into limestones, and converted the carbonate into sulphate 

 of lime. The origin of the Salt Range gypsum cannot, however, 

 we conceive, be explained in this way ; for if sulphuric acid vapours 

 permeated the marl, they would in all probability have produced 

 partial decomposition of the salt into sulphate of soda, an impurity 

 not to be found in the mineral The almost entire absence too of 

 carbonate of lime from the gypsum, strengthens the belief that it 

 was originally deposited as such. 



On tracing the limestone upwards, its beds become thinner and 

 less crystalline, and alternate with thin beds of dark magnesian 

 micaceous sandstones and shales. At the upper limit of these in the 

 central part of the Eange and Chichalee Hills as well as at Kaffir 

 Kote, a few thin beds of a compact slaty limestone generally of a 

 dark grey colour occur, and seem to mark the transition into the 

 next division. 



h. Grey Sandstone and Shales, 



The beds forming this series consist of micaceous fine grained 

 fissile sandstones alternating with beds of dark bituminous shales. 

 Towards their upper limits the sandstones become more compact and 

 of a reddish colour, alternating frequently with beds of slaty lime- 

 stone similar to those forming the top beds of the division of the 

 series last described. In the upper compact sandstones, ripple 

 markings are common, and in the Bukh Eavine above Moosakhail we 

 detected a most distinct exhibition of markings similar to those 

 produced by rain or hail falling on sand or mud, when in a wet or 

 pasty state. These occur on the upper surface on a bed of sand- 

 stone, and were traced along its strike for a considerable distance. 

 The bed dips under other beds of a similar sandstone which present 



