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Records of the Geological Survey of India. 
[vol. v. 
strong bed, 10 to 15 feet thick, of Lameta limestone, resting directly on the sandstones 
and clays of the Jabalpurs ; and upon it rests the trap, forming a second scarp; only at two 
or three spots one finds between these a remnant of a sand identical with the top bed on the 
observatory hill. In normally bedded rocks one would primd facie conjecture from such a 
section that the limestone here was the upper band of the ridge, requiring, of course for the 
non-appearance of the lower beds, the supposition of original overlap, with subsequent change 
of bed. On the ground, however, one cannot resist the conclusion that the limestones fac¬ 
ing each other on opposite sides of the little valley are the same baud, they so exactly 
correspond in every character; so that one is forced to account for the discrepancy otherwise, 
by the absence of all the middle beds of the ridge. The identification of the limestones on 
opposite sides of the valley, and their exact correspondence in level, sets aside the intro¬ 
duction of any abrupt change of bed at this point, so that the difficulty at first brought to 
notice of supposing the original dying out of such deposits as those of the middle beds of the 
ridge meets us now within the Lameta group itself; and the contrast of thickness and of 
level is so groat that one has to suppose a contemporaneous denudation to have assisted the 
irregularity of deposition, so as to admit of the top and bottom beds of the group coming 
together within such a short distance; a general undulating disturbance having still further 
increased the apparent anomaly of the actual features. 
The considerations stated in the last paragraph, by bringing the chief discrepancy 
within the group itself, would seem to dispose of the main point at issue—the unconformity 
of the trap on the Lamdtas. But such is not the case, even for the particular section under 
notice. The top sandstone is in force on the observatory hill, and again so to the south 
of the Paehperi flexure ; and it continues so beyond the Marjadlia valley to the south-west. 
On the Paehperi terrace, however, between the two first of these localities, one finds the 
nearest remnants of it, and this only locally between the trap and the limestone. Its 
absence is most reasonably accounted for by denudation. 
There are some local sections near Jabalpur independently involving the conclusion 
of a pre-trappean denudation of the Lametas. The ridge on which the European hospital 
stands is formed of Lameta limestone. In the river, a quarter of a mile to the east, the 
limestone associated with mottled sands reaches from the water’s edge to some 50 feet on 
the hill-side. In both positions there is a capping of trap; but between the two, on the 
north face of the rising ground, the trap reaches to a lower level. Again, in the reverse 
valley, to the north-east of the Marjadlia water-shed, the trap reaches nearly to the stream 
on the south-east side, at a much lower level than the Lameta limestone within a few yards 
of it on the north-eastern spur of the observatory ridge. 
The views illustrated in the foregoing remarks upon the sections at Jabalpur are briefly 
these : that the Lametas are clearly pre-trappean ; that there is good evidence for a slight 
pre-trappean disturbance of that group; and, that there is conclusive evidence for pre-trap¬ 
pean denudation. 
The local denudation of the Lameta group would not be of much significance as an 
indication of any partial separation of it from the trappean formation ; for, as Mr. Blanford 
has himself shown, the inter-trappeans have also suffered denudation before their inclusion 
by the trap. Mr. Blanford indeed, did not propose any separation of the Lamdtas from 
the inter-trappeans, hut rather, through their connection, to establish the cretaceous, rather 
than the tertiary age of the trappean formation; the correspondence of the Lametas with 
the Bagh beds being the point he most insisted on. And, certainly, the petrographical homo- 
logy of these groups is very striking. The considerations here offered tend to confirm 
that identification. 
