86 WYNNE : GEOLOGY OF THE SALT RANGE IN THE PUNJAB, 



The thickness of this purple group varies somewhat, but its prevalence 

 Thickness and distri- ^^^ ^^^r the eastern part of the range is very con- 

 ^'^*io'^- stant ; here it generally forms the first cliff rising 



out from the talus or broken ground^ as at Tilla, Chambal (east), along 

 the escarpment from Jalalpur towards Pind-Dadun-Khan and away to the 

 west. In this direction it gets very gradually thinner and no longer shows 

 itself so prominently amid the dislocated masses of other rocks, but along 

 the edge of the plains traces of it appear the whole way to near Musa- 

 kh^l, while in places within the glens it seems to have quite died out. 

 From this part of the range to the Indus it cannot be said to exist, at 

 least not in its usual form, being replaced by a clayey conglomerate of 

 metamorphic pebbles. 



The group has always proved unfossiliferous, nothing more than 



obscure and doubtful traces of fucoids occurring 

 UnfossUiferous. , . 



in it, and these but seldom. * 



The thickness of the Furple sandstone group varies from two hundred 

 to about four hundred and fifty feet. 



Silurian. 

 jVb. 5. — The Oholus or 8ipJionotreta beds show prominently in 

 all the eastern sections, forming an inclined talus 

 along the top of the purple sandstones ; and exposed 

 as belts in the cliffs or caps to projecting spurs.* They consist of dark or 

 blackish sandy shales drying of a dull purple colour, full of black glisten- 

 ing polished surfaces on the planes of lamination. 

 They are often micaceous and interstratified with 

 crystalline calcareous glauconitic-looking layers or sandy and conglome- 

 ratic bands, but the dark shaly character generally distinguishes the 

 zone, which is much better defined in some places than in others. 

 Strong ripple marks are seen occasionally. 



In two places — one in the Khewra gorge above where the fresh water 



is taken off for the use of the miners, and the 



Organic remains. . . . , o 



other in a deep ravine nearly a mile east oi 



( 86 ) 



