CHAP. 2.] KADAPAH RORMATION.—PAUPUGNEE BEDS. 161 
The limestones are principally very fine grained and compact in thick 
and thin beds, and are more or less silicious, and 
Character of limestones. 
occasionally magnesian in their constitution. 
They are usually of pale grey colors; but pink, red, and greenish beds 
are not at all uncommon. 
They are often frequently banded with white semi-opapue calcedonic 
Silicious bands of Chert, which when weathered presents a peculiar 
Solitoid structure. oolitoid structure. That is, these silicious bands are 
mainly made up of minute globular bodies consisting of concentric 
layers. No organic structure has been recognised in these little 
spheroids; nor is there any visible nucleus; they appear to be simply 
concretionary, and were possibly produced by the whirling of particles 
of sand or other hard material in the silicio-caleareous waters of the 
time. They are generally large enough to be clearly recognized by 
the eye, but the rock requires to be closely looked at. Unweathered 
pieces of the caleedonie chert, so common in the western slopes of the 
hills immediately west of Ryalcheroo, do not show the slightest trace 
of this peculiar structure. Not only does this structure show in the chert 
bands, but there are frequent layers of fine 0 quartzites which are 
full of the little spheroids. On weathered surfaces, they have frequently 
fallen out and left minute globular cavities in the rock. 
From the Penn-air northwards, the limestones become more silicious 
and are gradually replaced to a great extent by 
RES meloigs the beds of the caleedonie chert and fine homo- 
geneous quartzites, until north of the Puspulla 
valley there is hardly any limestone except near, or at, the top of the 
series. 
The lowest beds are generally red sands and shales, which are often 
ferruginous. Then there are calcareo-sandy beds: and above these the 
limestone beds, with their silicious bands and segregations, and inter- 
calated purple earthy slaty shales, or clay slates. 
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