GEOLOGICAL FORMATIONS. 45 



Again, west of the Habb river, forming 1 the boundary of Sind near th e 

 sea, the whole Khirthar formation appears composed of shales, marls, 

 and sandstone, closely resembling" in character those of the lower Khir- 

 thar group west of Upper Sind, and an enormous thickness of similar 

 beds is found extensively developed in Makran. 1 



4. Khirthar group. — Although this group, named from the great 

 frontier range of hills already noticed, is, when the underlying shales 

 and sandstones are excluded, inferior in total thickness to several 

 other sub-divisions of the tertiary series in Sind, it comprises by far 

 the most conspicuous rock, the massive nummulitic limestone. Of 

 this formation all the higher ranges in Sind consist. It forms the 

 crest of the Khirthar throughout, and all the higher portions of the 



Laki range, of the Bhit and Badhra ranges south- 

 Distribution. 



west oi Manchhar lake, and or several smaller 

 ridges, and consists of a mass of limestone, varying in thickness from 

 a few hundred feet in Lower Sind to about ],000 or 1,200 at the Gaj 

 river, and probably 2,000, or even 3,000, further north. The colour 

 is usually pale, either white or grey, sometimes, but less frequently, dark- 

 grey ; the texture varies from hard, close, and homogeneous, breaking 

 with a conchoidal fracture, to soft, coarse, and open. Ordinarily, the 

 nummulitic limestone is tolerably compact, but not crystalline, and chiefly 

 composed of Foraminifera, especially Nnmmulites, whole or fragmentary ; 

 corals, sea-urchins, and molluscs also abound, but the two latter very 

 frequently only weather out as casts. 



Throughout Northern Sind, except near Hohri, no beds are seen 

 beneath the Khirthar limestone, and the rocks which crop out west of 

 the Sind frontier from beneath the main limestone band have already 

 been described. The remarkable range of low hills, surrounded by Indus 

 alluvium, and extending for more than 40 miles south from Rohri, 

 Lowest beds in Eohri consists of nummulitic limestone having a low dip 

 hlUs ' to the westward, and beneath the limestone 



forming the eastern scarp of the hills, on the edge of the alluvial plain, 



1 Eastern Persia, Vol. ii., pp, 460, 473. 



( 45 ) 



