CHAP. 1.| KARNÜL FORMATION.—KHOOND-AIR GROUP. 51 
It appears then that the lower members never extended very much 
beyond the present boundaries,—on the western side of the Khoond-air 
valley at least; for there is the thinning out at Koilkoontla and 
Banaganpilly, as well as the just related case of the Oondootla plateau. 
On the eastern side of the Khoond valley there are also indications of a 
like thinning out of the whole group in gentle undulations up to the 
bases of the mountains. "This is all, however, very negative evidence : 
and it must be remembered that the purple shales are really showing a 
tendency to thicken out exactly where the limestones are thinning. 
The absolute greatest thickness of the Koilkoontlas at any point 
has not been made out, but there are sections show- 
ing 192 feet, and this is not the full depth in such 
eases. The particular case is on the east side of the Nundyall valley, in 
Thickness. 
its southern half, just on the Mootialpawd stream, where there is an out- 
crop of banded beds of limestones. 
It is about here, and so in a southward direction, that the sharper 
undulations and squeezed-up arrangement of this limestone group, and 
the next below it, begin to show in great force. And with this 
alteration in the general lie of the rocks some 
Re structures have been superinduced, which are not 
observable in other parts of their area. Besides being more or less 
cleaved, the limestones are rendered more compact and crystalline, so 
much so that it is often extremely difficult io recognize any difference 
between these Koilkoontlas and the lower Nerjee beds of the Jummut- 
mudgoo group, unless the section is cleared enough to show the inter- 
mediate shales, &e. The Nerjee limestones are, as a rule, compact and 
more crystalline than the Koilkoontlas, and they are more distinetly 
banded in light and dark layers. Now, along the boundary here, the 
Koilkoontlas are well banded, more crystalline, and weather like the 
Nerjees. They are also often much stringed with white carbonate of 
lime, partly in the planes of cleavage and partly in those of jointing. 
) ( 
