88 "WYNNE : GEOLOGY OF THE SALT RANGE IN THE PUNJAB. 



absent or inconsiderably developed ; but, possessing itself only a limited 

 lateral extension, gives place again in this respect to other beds. 



The group is characterised in many places, particularly to the. east- 

 ward, by the prevalence of certain hard, light cream-coloured, or whitish 

 bands of dolomite and massive calcareous dolomitic sandstone rook, 

 sometimes weathering after the manner of limestone, — sometimes showing 

 on the weathered surface strangely arranged markings like the sections 

 of flat lenticular patches of more compact texture than the rest, but 



never the smallest trace, so far as known, of any 

 Composition. i • ■, n • mi • 



kind of organic structure. This variety of rock 



has been called by Dr. Fleming magnesian sandstone, and stated to have 



the following composition'^ : — 



White quartz, sand ... ... ... ... 28-000 



Carbonate of iron with a trace of alumina ... ... 7"313 



Carbonate of lime ... ... ... ... 32-874 



Carbonate of magnesia ... ... ... 31-199 



Loss ... ... ... ,.. ... "614 



Total ... 100-000 



Doubtless its composition varies much, and this analysis appears 



to have been obtained from a highly calcareous and magnesian portion 



on Mount Tilla. The more massive beds frequently present a peculiar 



brecciated appearance, as if the rock had been broken by pressure and 



re-cemented. Associated with these harder beds are strong, light coloured 



sandstones, sometimes with oolitic layers or more flaggy bands, often 



separated by greenish and dark-coloured shales, the flaggy portions being 



occasionally covered with obscure lumpy fucoidal or annelidan markings. 



Unless the oolitic bands should be found to con- 

 Organic traces. ... 



tain microscopic organisms, the whole group would 



appear to be unfossiliferous otherwise than so far as stated. 



* I. c, page 255. As the rock contains more than 23 per cent, of carbonate of 

 magnesium, it ought, according to Cotta, to be called dolomite. Calcareous dolomite 

 sandstone would seem most applicable. 



( 88 ) 



