PART 4.] 
MedlicoU: Lameta Formation. 
119 
The denudation of the Lametas seems to have been much greater to the west than to 
the east. Prom Jabalpur they can be traced continuously for great distances round the 
Maudla plateau. That so moderately thick a formation should be so unbroken proves, at 
least, that the basin in which it was deposited was not there laid dry for any considerable 
period before the advent of the trap; if it does not indeed establish a closer connection 
with the volcanic outburst. It is very different to the westward : in going along the 
Narbada valley gaps become more and more frequent, and of greater length. In most of 
these cases it is demonstrable that the deposits are only denuded remnants, the volcanic 
rock frequently appearing close by at a lower level. 
The most westerly occurrence of these patches of Lametas— that can, at least, be 
included with the main area of that formation, there being a break of 130 miles on the 
south side of the valley between it and the infra-trappeans of Punasa and the Dliar Forest— 
is deserving of special notice for the peculiarity of its position, and because large vertebrate 
remains, though scarcely perfect enough for identification, have been found in it. It is not 
even quite certain that it is Lameta, because the supporting rook is not visible; but the 
lithological characters are so marked as to give much confidence in the identification. It 
forms a small inlier, weathered from beneath the trap in the bed of the Shcr river, under 
the village of Kareia. There is a deep pool in the river, on the up side of which massive 
trap forms a steep fall; while on the down side of the pool, twenty yards across, these 
Lameta beds rise abruptly, having a small dip down stream. The trap appears in the 
hank above them, resting on a highly baked red sandstone, the top surface of a greenish 
earthy rock, which is confusedly associated with a more ordinarily pebbly sandstone and with 
a sandy pebbly limestone; a total thickness of about 15 feet. Within about fifty yards 
the trap again occupies the bed of the river, and some eighty yards lower down the water 
cuts a narrow gorge through massive Jabalpur sandstone, for about two miles. The cross¬ 
ing trap seems to he part of the same mass as that facing the strata on the opposite side of 
the pool: thus implying a steep face of denudation. If this patch of Lametas was ever 
continuous with the main area, it must have been through valleys now filled up by trap, 
for it is separated from the present Narbada valley by a broad raised area of Jabalpur 
sandstone. In this region the Lametas do not intervene between the trap and the Jabalpurs, 
even at very small elevations. 
If it he assumed that these patches of Lametas are indeed remnants of a once conti¬ 
nuous deposit, this feature of denudation in the western region becomes a very important 
one. At present I see no escape from that conclusion : these patches are all on the same 
approximate horizon, and there is in most cases no assignable reason for their original 
limitation as local basins. The suppositions of once intervening marks of older rocks would 
equally prove the great denudation. I think, moreover, we are hardly at liberty to suppose 
these local basins to have been determined by intervening trap-flows, for the reason already 
stated, that no single case has been observed of Lameta beds overlapping, however steeply, 
on trap. 
It is important to notice a precaution that must obviously he taken in applying this 
crucial test of the pre-trappean horizon of the Lameta beds. The Deccan trap is found in 
different regions of its very extended border resting upon metamorphics or other old forma¬ 
tions at every level, from the moderate elevation of the Narbada valley up to the highlands 
of the Western Ghats. Its local base must, therefore, bo presumed to he of different horizon 
in the formation at these different localities. It must so happen that on the horizon of 
the inter-trappean deposits, these should occasionally lap freely over the trap, on to the 
adjoining rocks ; and they would, moreover, in such positions assume the sandy, pebbly 
character so common in the Laradtas, and so rare in the strictly inter-trappean basins. 
