1853.] Report on the Geological Structure oftlie Salt Range. 353 



Tertiary, Miocene (?) Roclcs, greenish Sandstones, argillaceous Grits, 

 Conglomerates, and red and green Clays. 



[Resting on the nummnlite limestone there is observed throughout 

 the Salt Range a conglomerate of small rounded boulders of a simi- 

 lar limestone connected by calcareous sandstone. This passes into 

 a series of soft greenish sandstones, alternating with bands of con- 

 glomerate, in which small boulders of plutonic and metamorphic 

 rocks predominate. These bands are very numerous near the Indus 

 above Kalibagh where among the boulders a black porphyry (mela- 

 phyre) is very abundant. Along with the sandstones and conglome- 

 rates, beds of argillaceous grit and red and green clays occur, which 

 contain crystals of selenite and small veins of carbonate of lime and 

 quartz. 



The sandstones are highly calcareous, effervesce strongly when 

 treated with muriatic acid, which, after dissolving the calcareous mat- 

 ter, leaves a sand chiefly composed of quartz, felspar, hornblende, 

 mica and magnetic iron. In the neighbourhood of the nummulite 

 limestone, their surface is frequently encrusted with a slight saline 

 efflorescence, but this disappears in the upper beds. 



"Where exposed to atmospheric influence and to the action of 

 water charged with carbonic acid, the sandstones are extremely soft 

 and incoherent, but at some depth from the surface, many of the 

 strata are hard and compact, and of a dark grey colour. 



The thickness of the above strata is enormous, and cannot, we should 

 think, be less than ten thousand feet, having, wherever seen, a remark- 

 able uniformity of character. Fragmentary portions of the bones 

 of large mammalia, &c. are everywhere to be found associated with 

 silicified wood of a brown colour. These are most abundant in the 

 argillaceous grits which are often so hard as to form excellent mill- 

 stones. 



The harder beds of grey sandstone yield a remarkably handsome 

 building stone, though by no means likely to be a durable one in 

 many localities, on account of the facility with which water charged 

 with carbonic acid removes its calcareous cement and reduces it to 

 the strata of a slightly indurated sand. It has, we believe, been used 

 extensively in the construction of the various works along the new 

 Peshawur road west of the Bukrala Pass, where fresh beds have 



