EASTERN PLATEAU. 161 



Leaving the mines and proceeding along the upper gorge, the top 

 of the marl, which is all more or less gypseous, has in places a dull 

 purple colour (probably representing that portion of the group described 

 as "brown gypsum" by Dr. Warth). Flaggy bands of dolomite and 

 massive layers of gypsum also occur in the marl, the uppermost being a 

 white band of the last mineral, immediately beneath the " purple sand- 

 stone group/* 



Associated with this gypsum is the volcanic rock of Khewra, and 



near it are some grey gypseous and carbonaceous 

 Volcanic rock. ./ o./ 



shales, as already mentioned (page 75). This upper 

 portion of the salt-marl seems to be highly saline, for the stream which 

 comes from the plateau above as soon as it enters the deposit becomes 

 so charged with salts that the pebbles in its bed are all frosted over 

 with a thick incrustation, growing for some inches upwards in fantastic 

 pedunculated and other dendritic forms. 



Ascending this stream, its narrow ravine exposes a good section 



in the purple sandstone, marly or shaly as usual 

 Overlying rocks. 



below, and its upper beds forming the lower part 



of the cliffs between the glen and the plateau. Its thickness hereabouts 



is estimated at from 450 to 600 feet. The dark shaly zone above it is 



also well marked all along the cliffs. In the main ravine, where the 



track upwards leaves the stream bed, is the locality at which the Silurian 



fossils, 05oZm5 or (Si^-^o^o/^-eif^, where first discovered. 

 Silurian fossils. 



These little shells occur in numbers in dark sandy 



micaceous shale, but some layers contain them in greater quantity than 



others. No fossils besides these could be found in their neighbourhood, 



except obscure fueoids or Annelide markings on flaggy layers ; some of 



these layers are calcareous and glauconitic. 



The dark band which contains these fossils is here fully 150 feet 



or more in thickness. It is immediately succeeded by the magnesian 



sandstone band, as usual prominent in the cliffs and exhibiting well the 



northerly inclination of the beds, at angles of 35° and 40°. The group 



w ( 161 ) 



