CHAP. 3.] GENERAL CLASSIFICATION OF ROCKS. 91 
The KADAPAHS and KARNULS consist of a great succession of 
Gon ERES clay-slates, quartzites,* limestones, and shales, 
E OW ۰ with traps and trappean associates, constituting 
two unconformable series, the older of which is largely developed in 
the Cuddapah district, while the younger—if not equally extended 
over the Kurnool district—is very apparent in the neighbourhood of 
Kurnool town. 
All the rocks of these two formations are more or less altered; 
but they still plainly show their aqueous origin,— so much so that 
one of their members has generally been described by nearly all the 
writers previously referred to as a set of sandstones; and it is quite 
possible, from a mere examination of many hand specimens, for an ordi- 
nary observer never to have conceived that some of the groups are 
altered at all. It is even almost certain that the probable analogues of 
these rocks in other parts of India are to a great extent not altered ; 
under which circumstances of course, if the age of these widely separ- 
ated rocks be made out as one, the term ‘altered rocks’ can be easily 
considered as of local application to parts of the one great Indian form- 
ation whatever its distinctive name may be. For the present, how- 
ever, it is sufficient to know that all these rocks in the northern part of 
the Madras Presideney are altered: and that this general signification 
is only occasionally used in eontradistinetion to the much more altered 
and older crystallines of the gneissic series. 
The strangest feature about these formations is, that they should be 
; so entirely devoid of fossils of any kind, or even 
No fossils. 
of any evidence of life, such as impressions of 
* Itis perhaps hardly necessary to mention that the term quartzite is here used for 
altered rocks of the sand group, in which the origin and structure are still apparent 
to the eye. The different varieties are then describable by the old names, sand, grit, con- 
glomerate, and breccia, appended to the general term. Should the term ‘quartz-rock’ 
occur, it will never refer to silicious rock of such obviously detrital origin as those in 
question. 
