58 
Records of the Geological Survey of India. 
[VOL. V. 
explain the phenomena of rocks found in a tropical climate, but without its agency it 
appears difficult, in the present state of geological knowledge, to account for the Talchir 
boulder bed.* 
3. Damuda Group. 
Above the Talchirs, or occasionally resting upon the metamorpliic rocks without the 
intervention of any other sedimentary beds, are found a series of sandstones and shales, 
with beds of coal. The sandstones are mostly coarse grey, and brown rocks passing into 
grits. They are usually more or less felspatkic; the felspar being decomposed and converted 
into clay, and they are often ferruginous. Blue and carbonaceous shales, often more or less 
micaceous, and ferruginous shaley sandstones are characteristic of this group. Fossil plants, 
chiefly consisting of Ferns (such as Glossoptens , Pecopteris) Trizygia, Pquiselacece and 
Catamites, and above all peculiar stems divided into segments, believed to be roots of 
unknown affinities ( Vertebraria ), are frequently found. Most of the fossil species found, 
perhaps all, are characteristic of the Damuda formation. 
The peculiar interest attaching to this group of rocks is, however, derived from its being 
the only one in which workable coal has been found in the peninsula of India. All the coals 
of Raniganj, and the other fields of the Damuda valley, all thoso of the Narbadda valley, 
and of other parts of the Central Provinces, are in Damuda rocks. So far as they have 
hitherto been examined, the coals of Talchir appear to be of inferior quality to those of 
Raniganj, the Narbadda and some other localities, but the field in the Tributary Mehals has, 
by no means, been thoroughly explored as yet. 
4. Mahadeva ? Group. 
Above the coal-bearing series in the western part of the Talchir coal field, there is found 
a considerable thickness of coarse sandstones, grits and conglomerates, quite different in 
character from the beds of the Talchir and Damuda groups, and resting unconformably upon 
thorn. These rocks are usually coloured of various shades of brown, they are frequently 
very ferruginous, and the separate bods composing them are massive and not interrupted, 
as the Damuda sandstones frequently are, by partings of shale. They form hills of consider¬ 
able size in Radakol. 
It is by no means dear that these beds are the roprosontati ves of the group in the 
Narbadda valley to which the name Mahadeva was first applied, but there is a general 
sub-division of the rocks throughout the greater portion of the Indian coal fields into three 
principal groups. To the higher of these the term Mahadeva has been given in the Narbadda 
valley and in Orissa, and Panehet in Bengal, and until re-examination of the Orissa beds has 
enabled their relations to that of other coal fields to be more accurately made out than was 
possible when they were first mapped, it appears best to retain the name then applied 
to them. 
» In 1855 Mr. Blanford suggested (Memoirs, Geological Survey, India, i, p. 49) that these beds might have 
been deposited on a high table land, and that the association of the boulders was perhaps due to ground ice. 
The advance of cosmical theories since that time has rather tended to increase the possibility of periods of 
cold having occurred in the course of the earth’s history, some of which may havo been sufficiently severe to affect 
the tropics, or portions of them. The Talchirs have now been found over so extensive an area that the probability 
of their having been deposited at any considerable elevation above the sea has greatly diminished, and some observers 
are inclined to consider them marine, a view which I do not share, but at the samo time no other hypothesis, not 
involving ioe action, has been offered which accounts satisfactorily for their peculiarities. (Since this was written 
strong confirmation of Mr. Blanford'* views has been obtained, by finding in these Talchir boulder beds masses 
of granite of large size, the surfaces of which have been polished, scored, and furrowed precisely as are the 
masses of rocks or boulders, found iubeddod in, and transported by, ice-floes or glaciers. T. UldhiM). 
