104 BLANFORD : GEOLOGY OF WESTERN SIND. 



The lowest portion of the nummulitic limestone in the Sukkur and 

 Lowest beds of lime- Rohri Hills consists of white limestone, abounding 

 stone with nummulites. j n nummu lites, and closely resembling the higher 

 bed seen on the east side of the hills. The lower limestone is partly 

 rubbly, partly uniform in texture, but throughout soft and easily 

 decomposed, allowing the Foraminifera it contains to weather out, so 

 that they occur in large quantities strewed over the surface. The most 

 common are Nummulites granulosa, N. spira; N. vicaryi, and N. lyelli. A 

 large form of N. spira, closely approaching N. carteri in appearance, forms 

 a layer of some little thickness, 40 or 50 feet above the base of the 

 limestone. A peculiar, globose, thick, smooth oyster, with a straight 

 hino-e line and winged at the side, the upper valve sometimes rising into 

 a blunt spine, is very common. It appears to be a form of Ostrea vesi- 

 cularis [GrypTima globosa, Sow.). Casts of Ovulum, Conus, &c, also 

 occur. 



The whole bed varies in thickness from 60 to about 100 feet. As 

 already mentioned, the outcrop is chiefly confined to the scarp on the 

 west side of the range. 



The beds below the nummulitic limestone form a low slope between 

 hi muli- ^ ne li mes tone escarpment and the alluvium, on the 



tic limestone. wertern side of the range, from about 6 miles south 



of Rohri to within 4 miles of Kot Deji. These beds are very ill- 

 exposed, their surface being much concealed by the detritus of limestone 

 washed down from the overlying beds. Their uppermost portion consists 

 of pale green clay, with large quantities of gypsum in bands and veins, 

 and with occasional layers of a deep red clay. Beneath 40 or 50 feet of 

 clay there is a dark band of dusky-brown limestone, and then more clay. 

 The lowest beds seen were only observed south-east of Trimmo, and con- 

 sist of fine hard calcareous shale, buff or pinkish in colour, with im- 

 pressions of a Cardita, resting on soft white rubbly limestone abounding in 

 fossils, principally casts, and associated with shaly limestone containing 

 a band, barely a foot thick, of bright silvery-yellow argillaceous limestone, 

 containing a Pinna and other fossils. 

 ( 104 ) 



