1845.] from Pondicherry to Beypoor. 761 



again of equable diffusion throughout the entire mass of rock, are 

 matter of interesting enquiry. It is a well known fact, that heat un- 

 der fusion will contribute to the concentration of particles of copper 

 ore diffused through a matrix, and it seems probable these effects in 

 the hypogene rocks have been produced during their subjection to 

 metamorphic heat and crystallization. 



Foliated garnet and reddish felspar occur in the more quartzy part3 

 of the gneiss. 



In the steps of a large well in front of the Traveller's bungalow, 

 are a few blocks of a gritty sandstone, resembling the more con- 

 solidated portions of the loose sandstone imbedding silicified wood at 

 Trivicary. It was marked with brick red, and ochre yellow, having 

 bands. It is said to have been quarried about two miles off, and also 

 to occur near Verdachelum. This led me to infer the possibility of 

 the extension of the fossiliferous beds of Pondicherry in this direction^ 

 an inference subsequently verified by Mr. Kaye, ot the Madras civil 

 service, (Vide Madras Journal for June 1844.) 



The limestone in which the Verdachelum fossils are imbedded, 

 resembles more that of the Trichinopoly beds, and the pelagic shells 

 it contains are supposed to be of a rather more recent epoch than the 

 Neocomien, or lower cretaceous series of Pondicherry, but this is a 

 point not yet quite settled by the present talented Secretary of the 

 Geological Society, Professor Forbes. The limestone was found to be 

 associated with beds of an overlying sandstone, imbedding silicified 

 wood, precisely resembling that of Trivicary and Pondicherry. These 

 beds, I have little doubt were once continuous. 



It is a point of much importance to ascertain the fact of the lime- 

 stone beds being continuous or not, or whether the Pondicherry beds 

 occupy a lower place in the order of superposition than those of Ver- 

 dachelum and Trichinopoly. The Verdachelum beds lie between 

 Paroor, a village about seven miles WN W. from Verdachelum and 

 the town of Verdachelum itself, which lies about twelve miles S. by E. 

 from Wallundoorpett. If the account given me by the natives be 

 true, the sandstone beds extend to within two miles of Wallundoor- 

 pett. The boiling point of water gives the plain at Wallundoorpett 

 but little elevation, if any, above the surface of the sea. 



A lunar halo occurred here, the radius of which I found to measure 

 21° 30', sky hazy, slight sensible depression of the thermometer 2°. 



