AT.CYONAKIA OF SIND. 13 



"<rffi/ Group. — Upon the Nari group, almost throughout Sind, there is found resting 

 a mass of highly fossiliferous limestones and calcareous beds, usually more or less shaly, 

 always distinctly stratified, and easily distinguished from the limestones of the older 

 Tertiary formations by the absence of Nummulites. A superb section of the strata 

 forming this group is exposed on the banks of the Gaj river, the only stream which 

 cuts its way through the Khirthar range, and in the neighbourhood of which, west of 

 the range, the fine section of Lower Tertiary and Cretaceous beds, already noticed, is 

 exposed. From this river the present group derives its name. 



" On the eastern flanks of the Khirthar range, in Upper Sind, the Gaj group forms 

 a conspicuous ridge, the hard dark-brown limestone bands near the base of the forma- 

 tion resisting the action of denudation] far more than the soft sandstones of the Nari 

 beds, and rising every here and there into peaks of 1000 and 1500 feet, or even more, 

 escarped to the westward, and sloping to the east, Amru (the highest summit of the 

 Gaj ridge) being 2700 feet above the sea. Still the limestone bands, although so 

 conspicuous, are subordinate, the greater part of the group consisting of sandy shales, 

 clays with gypsum, and, towards the base, sandstones. Many of the bands of lime- 

 stones appear very constant in position, and may be traced for a long distance. As a 

 rule, they are dark brown in colour ; but one bed is white, and abounds in corals and 

 small Foraminifera (Orbiioides), whilst some of the darker bands contain Echinoder- 

 mata in large quantities. The uppermost portion of the group is usually argillaceous, 

 being chiefly composed of red and olive clays with white gypsum ; and these beds pass 

 gradually into precisely similar strata belonging to the overlying Manchhar group. 

 The passage-beds contain, amongst other fossils, Turritella angulata and forms of 

 Ostrea and Placuna, and the following : — 



Corbula trigonalis. 



Lucina (Diplodonta) incerta. 



Tellina subdonacialis. 

 Area Larkanensis. 



"All of these have allies living in estuaries at the present day. Area granosa,, a • 

 recent representative of A. Larkanensis, being one of the commonest and most typical 

 of Indian estuarine Mollusca. To these estuarine passage-beds further reference will 

 be made presently, when the relations of the Manchhar to the Gaj beds are discussed. 

 The Gaj beds at the Gaj river are very nearly 1500 feet thick ; but they appear to be 

 less developed to the northward in the Khirthar range, and not to be much more than 

 half the thickness named west of Larkana, where, however, they are nearly vertical, 

 and have probably suff'ered from pressure. In Lower Sind the Gaj group, like the 

 Nari, disappears to the eastward of the Laki range, where it is either entirely wanting 

 or else represented by a thin band, containing one of the characteristic fossils, Ostrea 

 multicostata, at the base of the Manchhar group. There is, however, a very large area 

 of Gaj beds north and north-east of Karachi ; and the appearance of the formation there 

 is somewhat diflerent from what it is in the Khirthar range ; for the greater portion 

 of the group consists of pale-coloured limestones, almost horizontal, or dipping at very 

 low angles, and to the east of the Habb valley forming plateaux 400 or 500 feet high, 

 bounded by steep scarps, which rise from the low ground of the soft Nari sandstones. 



