174 
Records of the Geological Survey of India. 
[VOL. X. 
upon shales as has been above mentioned. In regarding the latter as the younger group 
my views are, I believe, in accordance with Mr. Hughes’ opinion in reference to the similar 
and very similarly circumstanced rocks of the Chanda district. Before proceeding to 
describe the physical relations of these rocks, so far as they have been examined, it only 
remains to point out the geographical areas which they occupy. The largest and most 
important area is that of the Chhattisgarli basin, the northern boundary of which stretches 
in a north-west direction from the neighbourhood of Sambalpur, passing Padampnr, Raigarh, 
Bilaspur, and Ratanpur up to the base of the Mandla plateau. Southwards from this 
with a very irregular eastern boundary, these rocks spread to unknown limits beyond the 
Raipur district. It is possible indeed that they will be found to be continuous with the 
Bus tar-Jaipur area to be mentioned below. The second area forms a considerable plateau 
which belongs partly to Nowagarh and partly to Ivarial. The third is also a plateau, and 
is situated on the north of the Jaipur district. To the south of this is the fourth area, 
which is included in both the Jaipur and Bustar districts. Besides these there are rocks 
of this age near Nowagaon and Aliiri to the south-east of Bhandara. 
Group A. — Sandstones, Quartzites, and Conglomerates. 
Although it is probable that members of this group will be found in the first area, they 
have not yet been separated in the extraordinarily crushed and disturbed sections of the 
northern boundary, where there are, especially in the Barapahar hills, rocks lithologically 
similar to those about to be described. The standard sections, than which no better are 
likely to be found, are met with in the Nowagarli-Karial plateau. This plateau is of an 
irregular oval shape, with the major axis running north and south. The area exceeds 750 
square miles. Tho general elevation averages probably about 1,500 feet above the surround¬ 
ing country, or say 2,500 feet above the sea. Certain peaks are, however, over 3,000 feet high. 
With a few local exceptions, the quartzites which form this plateau dip inwards away from 
tho gneiss.* On the west, in Nowagarh, the nature of the junction between these rooks and 
the metamovphics is very admirably illustrated in a series of peculiarly clear sections. In the 
best of these, in the Japen River at Doarpur and in tho Pairi River near Nangabahar, the 
quartzites are seen at tho level of the bed of the river resting directly on the denuded and 
irregular surfaco of the granitic gneiss. In the former se 't^ion the bottom bed of quartzites 
lias in places been eroded, and shows the bare granitic pick within the main line of the 
boundary. In the hitter section the quartzite boundary Lai. in the bed of the river, been 
cut back for several hundred yards, and the granite is seen, 1 pth on the banks and at the base 
of a waterfall 20 feet high, underlying the quartzites, the lowest beds of which fill up the in¬ 
equalities of the surface of the granite. Both to the north and south of the Pairi section, 
there are outlying caps of quartzite resting on several small granite Bills which are situated 
within from a quarter of a mile to a mile to the west of the main line of boundary. 
In these sections, especially in the first mentioned, we find traces of a black carbonaceous 
skaly bed in association with the quartzites. This bed is of importance, as marking a definite 
horizon, and will be referred to on a future page. 
From the Maliva hill round the northern end of the plateau to Tarnot, and thence to 
Borkot, we do not find exactly the same relation existing, hut the boundary is still a natural 
one. The original bounding rim of crystalline rocks which limited the basin of deposit is 
here in a great measure still conserved, and the elevation at which the line of junction occurs 
constantly varies, thus alfording evidence of internal overlap between the beds of quartzite 
along the margins of deposit. In some instances the granite is capped by the higher beds 
* A glance at the Atlas Sheet will bIiok the basil,-like character of the top of this plateau. The miinereua 
rivers emerge from it over falls and through deeply out gorges by which their waters reach the level of th« 
surrounding country. 
