CHAP. 1.] KARNÜL FORMATION.—KHOOND-AIR GROUP. 45 
occasionally so clayey and recent-looking that the calcareous mud-stones 
and clayey shales of the Khoond-air valley might be supposed to belong to 
a much more recent set of beds than those they are lying on. The shales, 
&e., are of a red-purple colour generally, purple always, and are at times 
seamed with pale turquoise-green calcareous layers, or thin bands of 
EN limestone. "Towards the northern part of their 
area they are crumbly and earthy, hard and soft- 
banded, cleaved calcareous shales—as in the long canal-cutting across 
the watershed between the head waters of the Khoond-air and the 
Bowanassi stream. In fact, towards the north this member of the 
Khoondairs becomes more compact and stony, while, as we proceed 
southwards, it is found to be more clayey and shaly. In the southern 
parts of the valley too, particularly in the Cuddapah basin, the Nundial 
shales are more or less cleaved, and might, down there, be called soft 
purple calcareous shales. They are always calcareous, that is, they 
effervesce on being touched with dilute nitric acid: and this is a peculiar 
feature as distinguishing them from the subjacent Owk shales and some 
of the finer shales in the kapAPAH ROCKS which assume the same red- 
purple color. They are easily distinguishable from the limestones below 
them both in color, texture, and composition ; yet they graduate down- 
wards into these by shales into shaly limestones, so that they appear to 
be a continuation of one deposit, of which the original materials became 
different as the formation increased in thickness. Indeed, it is very 
doubtful whether there is sufficient reason for separating this group into 
two members: excepting, perhaps, that they are so different looking, and 
so well seen in their different aspects over the valley, that it would 
sound absurd to hear manifestly argillaceous shales with only a small 
amount of lime in their constitution, called limestones, when close by 
there are massive beds which are as manifestly true limestones. As 
will be seen a little further on, there is some slight reason for the 
division of the group; but even as a matter of convenience, when 
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