70 
[VOL. IV. 
Records of the Geological Survey of India. 
Nimar (taking them in order from east to west), which are in great part on alluvial and 
tertiary deposits, with a narrow belt of older rocks along the southern side ot the valley. 
South of the Narbada valley rise the extensive highlands constituting the Satpura range, 
or its continuation, which are in great part formed of the Deccan traps resting upon 
crystalline rocks, or upon sandstone and other rocks of later date. Of this region Mandla 
occupies the extreme eastern end, bounded by the steep escarpment of thetrappean plateau, near 
to the edge of which the Narbada river has its source at Amarkantak. Along this same 
range to the west lie parts of Balaghat, Seoul, Chhindwara, and Betiil. South and 
south-east of the Satpura ranges lie the remaining districts. Bilaspur, Raipur, and 
Sambalpur lie in the great drainage basin of the Mahanadi. The two former occupy the 
low plain country of Chhattisgarh, formed principally on rocks hedieved to belong to the 
Vindhyan series, with a part of'their area covered by coal-bearing rocks. Sambalpur is in a 
rugged jungly country comuosed of crystalline and metainorphio rocks. The great drainage 
basin of the Godavari, on the other hand, includes Nagpur, Bhaucfara, Wardha, Chanda 
and Sironcha. These districts have no very considerable elevation. The two first are prin¬ 
cipally on gneissose rocks, with much trap in Nagpur: Wardha is almost entirely on trap- 
rocks; Chanda and Sironcha have a very varied structure, including more or less of all 
the formations that have been named. 
Geological groups. 
Crystalline and nictimiorphie rooks. 
Sub-metaraorpliie rocks. 
These formations may bo noticed in ascending order. The crystalline and metamorphie 
rocks have not as yet been described in any great 
detail. Gneiss of different varieties, often highly 
granitoid, predominates. The frequency with which 
these rocks appear shows how closely to the surface they form the substratum of the whole 
area. They are found at intervals all round the irregular boundary or border of the trappean 
rocks, rising in several places nearly to the full height of the plateau. The principal areas occu¬ 
pied by them are in Nagpur and Bhandara and in Betiil. Also in Sambalpur a very 
large area is formed of these rocks; hut this is naturally connected with, and belongs to the 
great Gneissic area of Bengal. In obscure relation to the gneiss there occasionally appear 
sub-metamorphic rocks, schists, slates, and quartzites. 
These may be seen at many points along the borders 
of the Narbada valley, from the north-east of Jabalpur into Ninuir. 
The great Vindhyan series of strata which form so prominent and important a feature 
in the geology of Hindustfin are the next deposits 
Vindhyan series. . • j» 1 • , 1 j. 1 n 
m succession of age ioimd m the Central -Provinces. 
There is, however, a wide and complete separation of these from the gneissose rocks. They 
are universally unconformable to the latter, and they exhibit little or no mineral alteration, 
and only very locally any marked mechanical disturbance. The range or escarpment, from 
which the name of the series has been adopted, forms the northern boundary of the N ar- 
bada valley, and the districts of Sagar and Damoh are occupied by the upper member of 
the series—the lihdnrer and ltcwd groups. Each of these groups consists of a strong band 
of sandstone resting upon shales with subordinate limestone—an arrangement which, coupled 
with the nearly horizontal position of the beds, has, through the operation of denudation, 
produced the peculiar surface features of the country, namely, local plateaus bounded by pre¬ 
cipitous scarps, overlooking broadly undulating valley-plains—features oven better seen in the 
Rewa country. The, Bijei&ghogarh pargana in the north-east corner of the Jabalpur 
district lies within the geological region of the Son valley, where the Lower Vindhyan rocks 
are so well exposed: they consist of less uniform alternations of shales, sandstones, and 
banded limestones, with some peculiar compact silieious (chorty and jaspery) layers, very 
homogeneous and regulnrh bedded. Along the entire southern margin of the Vindhyan 
