۲ 
CHAP. 3.] KADAPAH FORMATION.—CHEY-AIR BEDS. 203 
might be due to denudation simply; only it should be a very abrupt 
form of denudation, especially on the south side of the hill. It would 
be strange how the shales of the summit could have been deposited so 
evenly from the bottom to the top of the hollow in the trap; though it 
is just as hard, on the supposition of intrusion, to understand how they 
could have remained so with a great volume of voleanie matter bursting 
up through them. 
Taking then the stratigraphy of the whole of this sub-group into 
account, the traps certainly seem to have been 
Considered generally, 
the traps are mostly con- only partially or locally intrusive, though much 
temporaneous, partly in- 
OTE more so in their action on the subjacent Poola- 
vaindlas and the group beneath them: while they were generally poured 
out contemporaneously with the deposition of the Tadapurtee slates. 
Local intrusions are evident in the two regions above referred to, viz., in 
the Beddadoor hill and to the east of Yadakee; and it may possibly be 
that these were near centres of ejection, traces of which are to be 
looked for in vain in any other part of the field; yet they must 
have existed somewhere, possibly in the neighbourhood, for there are no 
traces of trap beyond this region, except that of dykes in the erystallines 
outside, and these are not connectable in any way with the traps of the 
KADAPAHS. | 
The Poolumpett Slates with limestones. 
The thin band, some 200 feet or more, of slates under the 
ear ae quartzites of Polleonda (south-east of Cuddapah) 
tives of Tadapurtee which, as stated in the last section, may be sup- 
m posed to answer to the Tadapurtee slates, is con- 
tinued in its outcrop southwards at the base of the western slopes of the 
Polleonda range, and eventually spreads out in great force over the 
valley of the Chey-air in the Nundaloor* and Poolumpettt country. Here 
* Nundaloor, a large village on the left bank of the Chey-air, near a station of that 
name on the north-west line of the Madras Railway. 
+ A cusbah or native Magistrate's village of the taluq. 
( 208 ) 
