PAST 4.] 
Ball: Mahanadi basin and its vicinity. 
183 
The same limestone is seen near the junction of the Sumpai with the Ebe, where it 
occurs in horizontal beds, abutting against a vein of coarse granite. 
Area in the Mahanadi Valley to the North-west or Sambalpur.— In this area, 
which is bounded on the north by the coal-field and on the south by the Vindhyan rocks, 
there is a considerable variety of both schistose and granitic beds : of the latter, the most, 
common is a granular-looking, but really finely porphyritic variety. But, perhaps, the 
leading feature presented by these rocks, especially in the area to west of the Ebe, 
is due to the presence of several strongly-marked bands of quartzite, which form a series of 
ridges, with an almost constant strike to north-west south-east. The most remarkable of 
these is the one which culminates in the Sunari H. S. peak (1,519 feet). The rocks occurring 
in this hill are protogine granites, covered by the quartzites and blue-aud-rcd sandy schists, 
which dip to north-east at about 80°. The schistose beds have a decidedly sub-metatftorphic 
aspect, but cannot be separated from the gneissose rocks. On the same liue of strike occurs 
the long ridge of quartzites, which bounds the coal field north of Kudderbuga. There are 
several parallel ridges to the above, with vertical bedding, which traverse the metamorphic 
area north of the Mahanadi. In some places these quartzites are quite vitreous; in others, 
distinctly granular, and not readily to be distinguished lithologically from certain beds of 
the Viudhyaus. 
Area South of the Mahanadi (Dukin-Tie). —The rocks of this area, so far as they 
have been examined, consist principally of granitic gneisses, which, however, present no very 
leading or prominent features, save that in the neighbourhood of Barpali, and perhaps 
elsewhere, trap-dykes occur in some abundance. Generally speaking, traces of volcanic action 
in the region under description are of extreme rarity. 
Patna and Bodosamae Aeea. —Throughout this area the principal hill formers are 
several varieties of garnetiferous gneiss. In the neighbourhood of Bolangir there are felspathic 
granites, which, over a limited area, are characterised by including lenticular masses of limestone, 
with which wollastonite is often much mixed. Close to the village of Daramgarh, and also 
at Domaipali, there are graphite schists. The graphite, being merely a constituent of the 
schist, is of course not of very puro quality. Remarkably fine rock-crystals occur in some 
abundance near Bijkomar, to the south of Bolangir. They appear to occur in a nest in vein 
quartz, but no matrix was seen in contact with the nest as at present exposed. 
Karial Aeea. —In the northern part of this area the crystalline rocks consist chiefly of 
massive porphyritic granites, which are occasionally traversed by eurite veins. 
Towards Kuinuna a definite strike to about 20° east of north becomes apparent, and the 
porphyritic granites, which often include pink felspar and a green chloritic mineral, alternate 
with occasional beds of garnetiferous gneiss. 
At Karial town and its neighbourhood the rocks do not continue to strike as above, hut 
from east to west and east-south-east to west-north-west become the prevailing directions. 
To the east of Karial, at Tukla, and thence towards Ranipur Jural, a. fine felspathic slightly 
garnetiferous granite occurs in bosses, some of which are of enormous size and perfectly 
symmetrical shape. 
The Chaoria hill, to the south of Karial, rises to an elevation of over 3,000 feet, and from 
a long distance off its massive scalped outlines form a prominent feature in the landscape. 
This hill, and most of those in the group to which it belongs, is formed of garnetiferous gneiss, 
Ivalahandi Area. —The rocks of the Tel and Hathie valleys in Kalabandi are, probably, 
to a great extent, similar to those just described ; but in the billy portion of the eastern half 
