PART 4.] 
Ball: Mahanadi basin and Us vicinity. 
177 
That they are unconformably overlaid is probable from the amount of disturbance they 
exhibit as compared with the overlying quartzites. In their lithological characters 
they correspond with those of some of the rocks of group ( B) of the Chhattisgarh basin and 
Jaipur-Bustar area. This resemblance, so far as itis of value, is in favor of the view that the 
quartzites of group (A) are younger than the limestones, &c., of group (B). But in addition 
to this, we have tho physical evidence afforded hy the fact that the Karial-Nowagarh 
plateau quartzites occur in their original undisturbed position at a much higher elevation, 
1,500 to 2,000 feet above the limestones of the Chhattisgarh basin, the nearest points on the 
natural boundaries of both areas being only a few miles distant. 
Again, in the Jaipur-Bustar area about to be described, we have quartzites the base of 
which is at an elevation of 700 feet above the level of the rocks of group (B). 
Great faulting in the intervals between the localities where these beds occur might 
serve to explain these differences of level under the supposition that the quartzites were 
older than the limestones, &c. But in the absence of the slightest evidence for faulting, 
the more legitimate conclusion to be drawn seems to be that the quartzites of group (A) are 
really younger than the limestones, &c., of group ( B). 
Jaipur Area. —The only other locality in which rocks of the same age as the Karial 
quartzites have as yet been identified is situated on the north-east corner of the Jaipur pla¬ 
teau to the south of Deobogh. There they rest upon a pedestal of crystalline rocks which is 
from 600 to 700 feet above the main Jaipur-Bustar plateau, and therefore corresponds in 
general elevation with that of Karial-Nowagarh. This small plateau, which extends over 
about 150 square miles, has been much broken up by river gorges in which the crystalline 
rocks underlying the thin quartzites are at various elevations laid bare. The quartzites, so 
far as they have been examined, are lithologically similar to the upper beds of the neighbour¬ 
ing Karial-Nowagarh plateau, with which, indeed, it is most probable they were at one time 
continuous. 
Gh'oup B. — Limestones , Shales, and Sandstones .' 
The known limits of the Chhattisgarh basin, the principal area in which rocks of this 
group occur, have already been roughly indicated. It will only be possible to give here a 
very brief sketch of what is known of the rocks. 
Commencing description from the most eastern point where these rocks occur, and not 
pausing more than just to mention the fact of the occurrence of several small outliers, we 
find in the Barapahar hills, a few miles to the west of Sambalpur, an accumulation of shales, 
sandstones, and quartzites whose relations, not only externally to the metamorphic series, but 
internally with one another, is of a complicated nature, and which can only be understood 
after much mom time has been devoted to their examination than has hitherto been possible. 
This indeed is a region of special disturbance, and one which, when the detailed examina¬ 
tion is taken up, would probably be most profitably reserved for the conclusion when stand¬ 
ard sections had elsewhere been ascertained. The boundary of this area runs north-west¬ 
wards, crossing the Mahanadi at Padampur. In some places, massive vitreous quartzites, with 
bedding obscure or completely obliterated, while in others shales, with occasionally vertical 
bedding, occur in contact with the metamorphics. Occasionally these rocks dip towards the 
boundary at high angles, a state of things produced probably by intense lateral pressure 
combined with faulting. In some cases these dips appear to be reversed, being produced by 
the folding over of the beds on themselves. 
The opposing edges of the two formations, as exhibited in the Squi River and also in the 
Mahanadi at Padampur, pretty clearly show that a fault has contributed to produce the 
relations now existing. In the latter section, the line of fracture traverses the lines of strike 
