1837.] 



through the Northern Circars, 



67 



convolvulus grows. In this thick stratum of sand no shells are to be 

 found, except those thrown by the sea on its surface. Under it, how- 

 ever, a clayey stratum, the thickness of which it is difficult to ascertain, 

 contains a great many shells, both salt and fresh water. This is clearly 

 seen in the sides of wells ; in digging which they always come to this 

 clayey substratum, before water is obtained. 



Many of these shells are identical with those of mollusca now living 

 in the river and on the shore, besides the pelagic ones. The stratum 

 of clay with shells, extends three or four miles inland, where pits are 

 dug to procure them for lime ; and these fossils may be seen, even, in. 

 the soil thrown up by the large crabs which burrow in the ground. 



In the plain of Poondy we thus see phenomena similar to those 

 witnessed at Vizagapatam, and the same inferences may be drawn at 

 both places. There are frequent signs, along the eastern shore of the 

 peninsula, of estuaries, or shallow bays, having formerly existed, 

 into which rivers discharged their waters : thus the clayey stratum, 

 containing sea and fresh-water shells, must have been deposited. 

 When the catastrophe happened which heaved up to its present alti- 

 tude this part of India, the clayey bottom of these estuaries contain- 

 ing shells, was raised into the atmosphere, and, at the same time, the 

 hills around. The subsequent decomposition, and gradual decay, 

 of these mountains, has covered this stratum of clay with one of 

 sand. 



Poondv,' March II.— About a quarter of a mile north of the village 

 of Guirzinghee, two miles from Poondy, there is a ridgy hillock, two 

 miles from the shore, not more than 200 feet high, its direction east 

 and west, sloping gently on both northern and southern declivities j 

 with the village of Carvera at its northern foot. It is composed of the 

 usual gametic gneiss, stratified. The felspar, one of its ingredients, is 

 of the species called albite or silicious felspar, in a granular state, and 

 also in slender needle-shaped crystals (No. 58). The cleavage of this 

 gneiss is in the line of the seams, which renders it extremely useful for 

 architectural purposes, as it splits easily in the usual way of masses 

 with parallel surfaces. 



This rock/ to the touch has a harsh, rough feel, probably on account 

 of the great number of the crystals of silicious felspar. The albite 

 sometimes is in slender prisms, one or two inches long, particularly 

 when on the surface, dispersed through the rock without regularity or 

 any common direction ; many crossing each other forming a net work. 

 No mica enters into the composition of this gneiss, except a few plates 

 dispersed through the rock ; a few garnets, which are imbedded in the 

 albite or cleavelandite, are not always in regular crystals, some- 

 times being finely granular, which gives the rock a remarkable srlini- 



