PART 4.] 
Ball: Mahanadi basin and its vicinity. 
171 
established by the remarkable section at Patrapara, where the lowest bed is seen resting on 
the denuded edges of a coal seam and some other cases of a more general character. In 
further confirmation of this view, I met with several cases, more particularly at Tipapani 
near Landimal on the extreme west of the field, where a coal seam with associated sand¬ 
stones is unconformably overlaid by a pebbly grit of the upper series. 
Overlap unconformity exists on a large scale in the west. Except at Tipapani the rock s 
underlyiug these beds are either Talchirs or metamorphics, the edges of the Barakar 
beds being wholly concealed. 
That these rocks belong to two or perhaps even more groups is probable ; indeed, in the 
section of the Ouli River to the south of Patrapara, I thought I could detect some indica¬ 
tions of unconformity. We there find a thickness of not less than 600 feet, possibly much 
more, of yellow and white sandstones with purple clays ; these rocks seemed to be much 
more disturbed than the conglomerates which cap the neighbouring bills. 
The conglomerates, of which there is here a thickness of 800 feet, are all more or 
less ferruginous, and contain quartz pebbles with jaspery ironstone and in some cases nests 
of white clay. It is possible that these may belong to a distinct group, and their lithological 
charactei's suggest a connection with some of the local groups of the upper Gondwana 
system, more especially with those formerly included in the Mahadeva scifies. 
The above-mentioned yellow sandstones and purple clays are seou in several other parts 
of the area, more especially two miles east of Kondaikula, where they occur faulted against 
the Talchirs and are overlaid by ferruginous sandstones. In some respects they resemble 
Panchet beds of the typical Raniganj area, corresponding thus with some beds of the 
Kamthi group in the Chanda country. At Intosoro, on a horizon slightly higher than 
that occupied by these beds, there are sandstones and conglomerates and red clays which 
seemed to me to be precisely identical with rocks seen in the adjoining field near 
Hingir. On the whole, in the absence of fossils, it is only possibles to form a conjecture 
as to the affinities of these upper rocks, but the balance of evidence seems to favor the view 
that, while at least a portion of them may not improbably belong to the same age, i. e., Kamthi, 
as the rocks of the Hingir group in the adjoining field, the remainder may represent a group 
of the upper Gondwanas. I have already noted a certain resemblance to exist between the 
highest conglomerates and some of the Atgarli rocks; this, however, may only be accidental. 
Damuda Series. 
Kamthi Group .—In the published account of the Raigarh and Hingir field, a list was 
given of the fossils obtained in the rocks which were temporarily distinguished as the Hingir 
group. This list, con'ected after fm-ther examination by Hr. Feistmantel, includes the 
following species, which are considered to be quite sufficiently numerous and characteristic 
to admit of the correlation of the Hingir and Kamthi groups,—thus confinning the con¬ 
clusion which seemed probable from the lithological and stratigraphical characters : 
Eqtjistetace.e. 
Schhtaneura Gondwanensis (leaves and stalks). 
Vertehraria indica, Royle. 
Eilices. 
Sphenopteris polymorpha. 
Pecopteris sp. 
G1ossopteris indica, Schimp. 
GL Brawniana (?) Bgt. 
Gl. angustifolia, Bgt. (with marginal line). 
Gl. communis —and another species. 
