GEOLOGY. 29 



as usual, with strongly contrasting alternations of gray clay and thin 

 bedded dolomitic layers or reddish and white gypsum masses. The rock 

 salt is also of the usual Salt Range kinds, varying from earthy layers to 

 bands which afford particularly fine, large transparent crystals, some 

 measuring a foot or more on the side. The pure salt beds range up to 

 20 feet in thickness, and none of them that I have seen bear the charac- 

 teristic appearance of the gray Kohat salt. 



2. The Purple Sandstone. — This group has not been found in its place 

 overlying the salt marl at Kalabagh nor elsewhere except near Saiduwali. 

 Being simply a thick set of purple sandstones it does not admit of much 

 further description. 



3. The upper gypsum, and dolomite group. — This is a thick gray band 

 of very distinct aspect ; it comprises numerous alternations of thickly bed- 

 ded whitish and gray-spotted, granular, or amorphous gypsum, with 

 massive bands of gray dolomite and sometimes with layers of soft white 

 or yellow incoherent sandstone, and gray shale or clay. Some of the 

 gypsum is black and strongly impregnated with bituminous matter smell- 

 ing of petroleum. 



4. The Boulder group. — This varies somewhat in places; its lower 

 part includes dark gray tough shales or clays containing little fragments 

 of broken grass-like plants or leaflets ; above these are dark purple clays 

 and sandy beds, sometimes with alternations of red and white gypsum, 

 one or more layers containing bipyramidal crystals of quartz. At various 

 horizons, chiefly in the upper part of the group, are the boulder beds, 

 full of well-rounded metamorphic and crystalline blocks, amongst which 

 varieties of granitic rocks with red felspar are common. Some of these 

 blocks are highly polished, and on a few I observed superficial striation. 

 The blocks are occasionally of considerable size. 



5. The carboniferous group — Has all the main characteristics of 

 its Salt Range portion. It is of dark colour and sandy calcareous 

 nature below. Magnesian limestones and sandstones may occur at any 

 horizon, and the main mass is of limestone of dark gray or black colour, 

 sometimes of a clear pale gray, and sometimes in the upper part occurs 



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