HISLOP AND HUNTER NAGPUR. 359 



right, the traveller comes upon one deposit, which is there of a deep 

 red clay as at Katol, three or four times successively. 



From the remarks now made it will be inferred, that the stratum 

 in question is extremely varied. Not only is it of all colours and all 

 mixtures of tints, but it is of all kinds of substance, and all forms of 

 structure. At one place it is calcareous, at another siliceous, at a 

 third clayey, and at a fourth a compound of all three. Here it is 

 soft, and there indurated ; frequently the upper layer, which is next 

 the overlying trap, is hardened, while the lower part remains un- 

 changed. Here it is crystalline, there cherty, and elsewhere scoria- 

 ceous. In one spot it is full of fossils, in another and neighbouring 

 locality it is utterly devoid of all traces of ancient life. In one part of 

 a hill we see it six feet thick, but as we follow its line along the face 

 of the escarpment we may witness its reduction to little more than an 

 inch. I know not one constant feature that is characteristic of it. 

 In judging of its identity a very useful guide to follow is its position 

 between the nodular trap above and the vesicular trap below ; but 

 even this, as we have seen, fails us on the outskirts of the formation. 

 Extensive experience, that enables us to combine several criterions 

 that would singly be insufficient, is here, as in so many other cases, 

 the only sure help towards arriving at a correct decision. 



The greatest depth of the underlying trap, from its lower part 

 being generally concealed, it is impossible to ascertain. It is obvious 

 that according to its greater or less development the plain rises into 

 a gentle swell or increases to the dimensions of a hill. Near Takli, 

 at the spot where almost all the fruits have been discovered, it is 

 only a few inches thick, and a few yards from that locality it thins 

 out altogether ; whereas at Sitabaldi Hill, where it is observed to 

 rest on sandstone, it attains a thickness of 100 feet; and in hills 

 where its superposition on the sedimentary rock cannot be seen it 

 must be a great deal thicker. 



I have been thus minute on the appearances exhibited by the 

 overlying and underlying trap and the deposit enclosed by them, in 

 order that we may have a clear idea of their relation to each other. 

 The conclusions to be derived from my description I need scarcely 

 indicate. It is quite evident, that before either of the volcanic rocks 

 was poured out in our area there had been deposited on the sand- 

 stone a stratum which must have been at least six feet thick. Over 

 this there was spread a molten mass of lava, which hardened the sur- 

 face of the stratum, and itself cooled into a flat sheet of globular 

 basalt about 20 feet thick. After a period of repose the internal 

 fires again become active, and discharge another effusion, which in- 

 sinuates itself between the sandstone and the superior deposit ; and 

 accumulating in some parts more than in others, through force of 

 tension ruptures the superincumbent mass, tilting up the stratum 

 and scattering the overlying trap, or raising both stratum and trap 

 above the level of the plain, either leaves it a flat-topped hill, or with 

 boiling surge pushes up its summit gradually or by fitful effort. In 

 these convulsions, the more recent trap, where it has not tilted up 



