76 
Records of the Geological Survey of India. 
[vol. VIII. 
dikes and quartz veins or reefs. These are seldom connected with actual dislocations of the 
strata, but they often disguise the mineral characters of the rock, and thus obstruct the 
identification of isolated outcrops. 
The south boundary of the area under notice is the base of the sedimentary series,—the 
junction of the Talehir group with the gneissic and schistose rocks 
The southern boundary. forming the highland of Betul. For the most part the contact 
occurs in the low ground along the base of the hills of crystalline rocks. It forms an exceed¬ 
ingly indented outline, being in fact the intersection of two very irregular surfaces—the 
present ground surface with that of tho original floor of deposition of the Talchirs. The 
actual contact is frequently exposed; nowhere better than in the Phopas (at the south-east 
corner of the map): the gneissose schists are denuded in the bed of the river, and for several 
score yards along the left bank the Talehir boulder clay is seen resting flatly on a rough, sharply 
weathered, ancient surface. At some points this boundary seems to be a faulted one, as in the 
section of the Amdhana stream at the south base of theBhaorgarh ridge; the contact here is 
very steep and crushed, and is moreover on the run of the Machua, uorth-east to south-west, 
fault. In the west, at the head of the Bhoura and iSiiki valleys, the Talchirs rise to a consi¬ 
derable height, forming the upland about Kota, between the Bhaorgarh crystalline ridge on 
the south and the basalt-capped ridges on the north. The formation is splendidly exposed in 
the scarps of this small plateau, west of Mura village. The exact position of the southbound¬ 
ary has only been fixed at a few points of our area, the intermediate portions being left un¬ 
coloured in the present map. 
The northern limit of the area to be described is an arbitrary line in the great sandstone 
deposit overlying the coal-measures. These beds belong to that 
,1-lhem limit of map. portion of the Damuda series of the Satpura basin indi¬ 
cated in my former paper as the Motur horizon, in which carbonaceous matter seems to be 
altogether wanting (but reappearing in the overlying beds of the Bijori horizon). The clays 
of the Motur group are often slightly ferruginous. 
The Motur-Barakar boundary line is, on the whole, well defined. At several distant 
places, as Dolari and Kosmeri on the Tawa and below Sonada on 
Motur-Barakar boundary, ^he J3] 10ura stream, the contrast is very well marked between the 
hard white sandstones of the coal-measures and the softer earthy tinted rocks above. On the 
Tawa below its confluence with the Madina the distinction is not so marked. Some other 
parts of the boundary are only approximately accurate on account of the covered condition 
of the ground. 
The base of the Barakar group is very vaguely definable as a strict geological horizon. 
The characters of the two deposits are not only blended vertically 
Barakar-Talctir boundary. ^ interstratification, hut it would appear as if this also Occurred 
horizontally—beds of decided Barakar type in one place being represented by as decided 
Talehir rock elsewhere. TLus it may be that the line given is not truly equivalent in differ¬ 
ent parts of the field. This feature will be indicated in the descriptions of the different 
sections. 
The physical features suggest the division of the area into four portions : on the east a 
great fault quite detaches the Dolari outcrops from those lower 
Pom separate .uens. down the Tawa; the great Machna fault cuts olF this second area 
from that traversed by the Suki, and this again is separated from the Sonada outcrops in 
t he valley of the Bhoura by a steep ridge of indurated sandstone along a vein of quartz 
infiltration. 
