HISLOP AND HUNTER NAGPUR. oG9 



obvious that in places not a few the water of the lake must have been 

 so shallow as to allow the igneous rock which was poured out over 

 its bottom to rise above its surface into the atmosphere. We must 

 resort then to some other hypothesis than aqueous pressure to explain 

 the horizontalness of our trappean-hill tops, and a cause adequate to 

 the effect is the well-known law by which the surface of liquid bodies 

 is reduced to the same uniform level. To this law volcanic matter 

 is subject in spreading over an area either of land or water. If to 

 this it be objected, that then we should expect the surface of the 

 effusion to appear scoriaceous like modern lavas, it may be replied 

 that naturally all such light materials in the lapse of ages would be 

 worn away. 



VII. The Sandstone Formation. 



Under the amygdaloid, or, where it has not been intercalated, im- 

 mediately under the tertiary freshwater strata, is found an extensive 

 series of rocks consisting chiefly of arenaceous beds. 



A. The upper member of this series is seen at the foot of Sitabaldi 

 Hill, passing into gneiss, into which much of it, as well as most 

 probably all the lower members, have been converted. Without 

 enumerating all its localities, I may mention that a good section of 

 it is presented by a rivulet skirting the Lai Bag, where the layer 

 under the nodular trap has itself been rendered distinctly nodular. 

 It may be observed in the western division of the city of Nagpur ; 

 and it stretches in some places under the amygdaloid, in others under 

 the tertiary bed, but for the most part as the surface-rock, through 

 Takli plain to Bokhara. At Nagpur and in Takli plain the strata 

 are of friable sand intermixed with kankar, and variegated with a 

 deep irony-red and occasionally a purple colour. But it is at 

 Bokhara where we can understand it best. In one of the quarries 

 there we find it as at Nagpur, only with less of the colouring matter. 

 Going northward to another quarry, we see it on the way overlaid 

 by the lacustrine formation before described, which is capped by a 

 small rise of nodular trap. Arrived at the quarry, which is only 

 about 100 yards from the first, we find the same upper member of 

 the sandstone, now however no longer soft and crumbling, but so 

 hard that the hand-millstones of the country, which resemble Scottish 

 querns, are derived from it ; and the ferruginous matter, instead of 

 being diffused as blotches, is gathered into waving iron-bands more 

 indurated still. At this place these upper beds, which are about 

 25 feet thick and very coarse, contain angular fragments of a finer 

 sandstone which lies below. Near Bazargau the strata where exposed 

 are pierced with irregular holes, which seem to have been caused by 

 the action of rain and the atmosphere. At Kampti, situated towards 

 their top, and rising even to the surface through the soil, are im- 

 bedded huge blocks, some of them angular, but most of them 

 rounded and waterworn, which contain almost all the fossils that 

 have been procured from that interesting locality. At Silewafi?a, 

 towards their lower part there occur a considerable number of com- 



VOL. XI. PART I. 2 C 



