140 KING: KADAPAH AND KARNUT FORMATIONS. [PART I11. 
Dhoor. Asa general rule, however, there is no approaeh to the slate 
of commerce; the closest approach being only as flags or thick slabs. 
They cannot be chipped into blocks of any good size or shape, except 
with great care; jointing being almost as well developed as cleavage, 
except in the less frequency and closeness of the planes of division. In 
hammering most of the slates they may just as readily split along a 
plane of jointing (though not apparent to the eye) as along cleavage 
planes. Fracture always takes place by planes of cleavage or jointing ; 
very seldom along those of lamination. It is often extremely difficult 
to recognize lamination: occasionally utterly impossible, except by 
reference to the adjacent beds of quartzite. 
One of the groups (Cumbum slates), or rather a band 1n this group, 
is very largely mixed with quartz; but it is very diffieult to say 
decidedly in what planes,—occasionally in those of cleavage, and again 
in those of bedding. In the southern part of the Nullamullay region, 
as along the Budvail valleys of the Cuddapah distriet, the quartz 
was apparently always in the planes of cleavage; but north of this, 
between Poremaumla and Cumbum, the interlaminar spaces are charged 
with this mineral. 
The quartzites in all the groups of the KADAPAH series are, to all 
appearance, as a general rule, altered sandstones 
General character of 
qua and grits, being only conglomeratic to any marked 
extent in the lower groups. This appearance may deceive, as in a 
marked example, on the flanks of the hills north-east of Cuddapah, of a 
quartzite which, if it were not for weathered surfaces, might be taken for a 
uniform granular rock, whereas, in weathered masses, it is an exceedingly 
coarse conglomerate. Sufficient weathering, therefore, may not have 
been superinduced upon those homogeneous-looking beds of the other 
groups to bring back to light their original constitution. Still, there 
are frequent cases of complete weathering without any result but a true 
sandstone or grit: consequently, this character may be almost safely 
AOD 
