Art. XI.—Summary of the Geology of Southern India

Abstract

Geographical Position.—About nine miles inland of Pondicherry on the Coromandel coast, Lat. 11° 56′ N., are beds of limestone rising in gentle undulations, and running in a S.E. by E. direction, almost parallel with the coast, for a distance, as far as I was able to trace, of about four or fire miles. Of these strata no detailed account had been published up to the date of my visit in March, 1840. They are seen to crop out near the villages of Sydapett, Carassoo, Coolypett, and Vurdavoor, from a superincumbent tertiary lateritic grit imbedding large quantities of silicified wood, and of which a description has been given by Lieutenant Warren: who has, however, overlooked the fossil limestone. The beds of the latter dip very slightly easterly. The greater part of the surface of the limestone is concealed by the soil and vegetation. A short distance further towards the west it is again covered by beds of the silicified wood deposit, and both are underlaid by plutonic and hypogene rocks, which crop out near the village of Trivicary, and form the western boundary of the fossiliferous beds. Rolled and angular fragments of the hypogene rocks are scattered here and there over the limestone, as well as fragments from the silicified wood beds, and from the limestone itself; the surface of the latter has evidently been exposed by the denudation of the superincumbent beds. It appears in surface-worn tables traversed by innumerable fissures.