Ill On the Geological characters of the [July 



At the south eastern corner, the nearest point of the laterite forma- 

 tion to Madras, there are numerous pits, where the rock is quarried to 

 furnish material for the repair of the roads. After penetrating several 

 feet of gravel, they come upon the solid laterite, which is broken up 

 with a crow-bar, for which the employment of very great force is 

 necessary, the mass being previously softened by the affusion of water. 

 It no where is of the soft consistence of the laterite of Malabar, as 

 described by Buchanan and Babington. 



The laterite in this locality (No. 21) varies in no respect from that to 

 the northward of the lake. It is all of the true compact kind, and I no 

 where saw the large masses of conglomerate sand-stone imbedded in 

 the clay, witnessed in the nullah ; nor was there any appearance 

 of stratification. 



The same kinds of imbedded rocky fragments were found also at 

 this spot, with the following additions : 



1st. Granite, composed of quartz, felspar and mica : a single, small, 

 angular fragment (No. 22). 2d. Sienite, or sienitic granite, composed 

 of quartz, felspar and hornblende ; a large angular piece, in a disinte- 

 grating state (No. 23). 3d. A fine grained green-stone ; a large frag- 

 ment (No. 24). These were found among the fragments, which the 

 workmen had produced by their operations in the pits, and I cannot 

 say whether they were derived from the gravel or the compact laterite. 



I have met with no calcarious matter in the localities I have visited, 

 though I made particular enquiries on this point, as Dr. Heyne 

 mentions the existence of that mineral at the Red Hills.* I picked 

 up a single fragment of botryoidal kankar, to the south of the lake, 

 t>ut no where found it in situ. 



At the top of one of the lower eminences, imbedded in the gravel, 

 about a foot and a half from the surface, I found fragments of a rude 

 pottery, the composition of which is of the coarsest kind, being a dark 

 green paste, containing numerous grains of quartz (No. 25). These 

 fragments, thirty or forty in number, were irregularly disposed, some 

 pieces being vertically placed, others horizontally, shewing a confused 

 arrangement in the gravelly matrix. This circumstance proves the 

 gravel to be of recent origin. 



Dr. Benza informs me that fragments of pottery of precisely similar 

 composition, are found in the cairns on the Neilgherry Hills. It 

 appears to me to resemble none of modern manufacture. 



It is singular that no organic remains have been hitherto found in 

 the laterite itself, or in the gravel deposits. We might suppose that, 

 if the waters which held the matters composing these conglomerates in 

 suspension, had moved with great turbulence and rapidity, so great a 



Tracts on India, p. 114. 



