CHAP. 1.] |. PREVIOUS OBSERVERS. 3 
Though this is the area of rocks to be described, it must not, 
at the same time, be inferred that these rocks are confined to it alone ; 
for from what has been written by previous observers, and from an exa- 
mination of the rocks which my colleague Mr. W. 'T. Blanford has 
traced down to the Godavery, there is every probability that the same 
deposits extend and cover large areas up to and beyond that river. 
It would have been all the more satisfactory for the writing out 
Outliers still unex. OF this Memoir if the full extent of the rocks and 
plored. their absolute relations with other known forma- 
tions in Central India had been made out, but the complete insulation 
of the Cuddapah and Kurnool area, and the further delay which would 
be incurred by wandering over such a great extent of country, render 
this impossible for the present. | | 
Nevertheless, the field now to be described is a very large one and 
Be el ares. porfork perfect in itself, and it is hardly possible that the 
E meai examination of a, few further outliers of only 
small extent would make the history of the rocks any clearer, or the 
comparison between these and the North Indian deposits of like kind 
a less difficult problem than it still is. 
PREVIOUS ACCOUNTS. 
The structure and relations of the groups of rocks constituting 
the two formations herein referred to, have, for 
Already written of. 
| more than seventy years, been a fertile source of 
investigation and speculation with several observers, and it may be as 
well, before giving the results of the latest examinations, to record briefly 
the observations and conclusions at whieh they arrived. 
The earliest notice to be found having reference to the Cuddapah 
Geto: Mackenzie 20d Kurnool rocks is in an account* of a visit 
ee which was made by Captam Colin Mackenzie 
* Asiatic Researches, vol. V, p. 303. 
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Oo 
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