1853.] Report on the Geological Structure of the Salt Range. 261 



of that of the Salt Range, as well as of the calcareous strata of 

 Moosakhail. 



The rocks included under the term carboniferous present in the 

 Salt Range three divisions, which we shall proceed to notice. 



A lower limestone, calcareous sandstone, and shales. 



The lower beds of this deposit, when they rest on the Devonian 

 rocks, generally present the characters of a calcareous sandstone of 

 a light grey colour. This gradually passes into a limestone of a very 

 compact and generally crystalline character, varying from a light 

 flesh colour to dark grey, some varieties being nearly black. The beds 

 of this rock, in which occur irregular shaped masses of hornstone, 

 sometimes closely approaching to flint, are frequently parted by thin 

 bands of arenaceous shales. There are frequently a mass of corals 

 and corallines mixed up with shells. The limestones generally 

 abound in encrinites and large brachiopodous Mollusca, and in many 

 localities seem to be composed entirely of the disjointed stems of 

 the former. Their fractured surface presents generally a highly 

 crystalline aspect from the encrinite whorls being converted into 

 calcareous spar. 



Although generally a purely calcareous formation, in some localities, 

 especially towards the Indus and in the Chichalee hills, it seems to 

 become magnesian and to alter considerably in general appearance. 

 Wherever magnesia prevails, the limestone assumes a cherty aspect, 

 the strata are much disturbed, and frequently shivered, fossils be- 

 come very scarce, and the same brecciated appearance as is noticed 

 in the Devonian Dolomitic sandstone is very common. The occur- 

 rence of magnesia in the limestone is very local, and the same bed 

 may be observed purely calcareous and full of fossils at one point, 

 while half a mile beyond, it is charged with magnesia and scarcely a 

 fossil to be found in it. Although the transition from a calcareous 

 rock to a magnesian one is generally noticed along the strike of the 

 beds, the same change may be observed in some localities extending 

 in a vertical direction ; such phenomena have been observed by Sir 

 Roderick Murchison in the Alps, and it has been supposed that 

 the magnesia, subsequently to the formation of such limestones, 

 has been injected into them, and produced a metamorphosis. The 

 absence of fossils too amidst the magnesian limestones has been 



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