248 
MANGANESE DEPOSITS OP INDIA : GEOLOGY. [ ParT II : 
to obliterate any minor evidences of intrusive relations, 
partly by rolling or crusliing of the boimdaries of the 
two rocks, and partly by reactions producing mineralo- 
gical re-arrangement at the junctions between rocks of 
different chemical composition, as in the case of the 
special rocks formed at the contacts of the charnockite 
and khondaUte series in this very district^. But it 
must be admitted that in most cases there is little or no 
I evidence that the kodurite series has suffered much from 
earth-movements since its presumed intrusion. 
At Ramabhadrapuram there is exposed in one of the pits a band of 
quartz-microcline-rock which, since it contains the greenish blue apatite 
characteristic of the kodurite series, with which it is associated, may be 
supposed to form a part of this series. The structure of the rock is such 
as to suggest a pegmatite that has moved at the time of solidification. 
The only remaining argument in favour of the igneous origin of the 
kodurite series is the presence of two large xenoliths of crystalUne 
limestone in the masses of lithomargic rock atKodur (see page 1065). 
Their position is best explained on the supposition that they are masses 
torn off and brought up from below by the kodurite intrusion. 
The evidence in favour of the igneous origin of the kodurite series 
can therefore be summed up as follows : — 
(1) The mineralogical and chemical composition of the rocks, which 
could only with difficulty be explained on any other hy- 
pothesis (see page 261). 
(2) The signs of magmatic differentiation (see page 254). 
(.3) The supposed included xenoUths of crystalline limestone at 
Kodur. 
(4) The pegmatoidal variety at Ramabhadrapuram. 
(5) The varying horizon that the rocks of this series occupy in the 
succession of calcareous gneisses and khondalites. 
(6) The fact that in two cases, Chintelavalsa and Taduru, they are 
also associated with rocks that probably belong to the 
charnockite series. 
The only point that seems to be adverse to the igneous theory is the 
absence of any observed intrusive relations of the kodurite series 
with respect to the calc-gneisses and khondalites. This, as shown above, 
is easily accounted for. 
1 T. L. Walker, Rec. O. S. I.. XXXVI, p. 1^ (1907). 
