SOUTH- WESTERN PORTION OF KARACHI COLLECTORATE. 171 



imperceptibly into Khirthar limestones, and it is impossible to draw a 

 precise boundary between the two groups. In one place half way 

 between To-be-ka-lak and Tong (about 12 miles north-west of the latter 

 and south of some isolated hillocks of sandstone,) rusty brown sandstone, 

 with partially decomposed Nummnlites garansensis, and in the upper 

 part a large thin Orbitoides, is seen resting unconf ormably on the worn 

 surface of a yellow limestone. The latter is somewhat arenaceous, and 

 contains large white Orbitoides. Apparently this is another instance, 

 besides those previously mentioned, of a break in the Nari group, to 

 which both beds appear to belong. 



On the east side of the valley the thick bed of Orbitoides limestone 

 was not observed, but it may possibly have been overlooked. There are 

 hillocks of brown arenaceous limestone full of Nummulites sublavigata 

 and N. garansensis with some Orbitoides ; Pecten bouei also occurs, and 

 the large Echinolampas found at Pokran, Chorlo, &c, abounds in one 

 bed, doubtless the same as that seen on the opposite side of the Khir- 

 thar range. A little lower down is the zone of large corals at the top of 

 the Khirthar group. All these beds, except the last named, were also 

 observed in places on the west side of the valley, as at Gurano-jo-kal, 

 9 or 10 miles above Tong. 



West of Tong (Rath Nath), which is a rather larger village than is 



commonly found in so thinly populated a district, 

 Neighbourhood of Tong, . 



there is a small ridge formed by the Nari lime- 

 stone with Nummulites garansensis, Orbitoides, &c. This ridge can be 

 traced for a long distance north and south. The dip near Tong is very 

 high, as much as from 50° to 70°, and a great thickness of the limestones 

 and associated beds must exist. Immediately west of the ridge the dip 

 falls to from 5° to 10°, and a considerable distance intervenes before the 

 base of the Nari beds is reached. Some red clays occur, but in general 

 only the hard beds are seen at the surface. 



Just west of the ridge above mentioned and in the lower Nari beds 



a hot-spring arises, the flow from which is sufli- 

 Hot-spnng. 



ciently copious to irrigate a considerable tract of 



( HI ) 



