Page:Madras District Gazetteers - Anantapur.pdf/30
and partly forms the embankment of, the great tank at that place. A few brecciated quartz runs, such as Tellakonda, five miles south-east of Vajra-Karuru, deserve notice, for the white crests they give to various hills make them very conspicuous. Their orientation is very varied, but south-east to north-west is one of the courses most frequently pursued.
The north-east corner of Anantapur, including most of the Muchukéta line of hills, is occupied by rocks of the Cuddapah system, which continue northward into Kurnool. These are parts of the two lower groups of that system which make a great semi-circular band extending north-west and north from Cuddapah district inte Kurnool. The succession of formations occurring here agrees with that seen in the Pulivendla taluk of Cuddapah. Allowances require to be made for local differences in lithological character, but there is no doubt as to the true continuity of the groups. The great flows of contem- poraneous trap can be followed up right into the Kurnool district, and form an excellent index of succession. In the north-east corner of Anantapur, five miles north-east of Tadpatri, there is a small tract of Banganapalle quartzite capped by Narji limestone (of the Jammala- madugu group, Kumool system) which is of interest as being the most southerly point at which the diamond beds occur. No mines seem to have been made there however.
Of the economically valuable minerals diamonds come first. They occur occasionally on the surface near Vajra-Kardru in Gooty taluk but their source of derivation has not yet been satisfactorily ascertained, At Vajra-Kardru is a neck of blue rock which bears a strong superficial resemblance to the Kimberley ‘blue ground’. The Kimberley rock has however been shown by Professor Carvill Lewis to be a distinctly new rock type (which has been named ‘Kimberlite’) and to be serpentinous, and derived from a true peridotite; whereas Mr. Philip Lake found! that the Vajra-Kartru rock is not serpentinous, cannot have been derived from a rock like Kimberlite and has been formed by the alteration of a basic reck and not of a peridotite. The prospecting which has been conducted at Vajra-Karuru is referred to in the account of that place in Chapter XV.
Corundum is reported? to occur at ‘Punighi’ (? Parige) near Hindupur ; in several places in Madakasira taluk ; at Danduvaripalle, Siddarampuram and its hamlet Pasalaru, Reddipalle, Atmakoru, Paramatiyaléru and Timmdpuram in Anantapur taluk; at Modtarla-
1 Records Geol. Surv. Ind., xxiii, 69—72. See also vol. xxii, Pt. 1, 3949. 2 Man. of Geol. of India (Econ, Geol.), Pt. 1, Corundum, by T. H. Holland, p. 36.