387 
of the Country between \ Tellicherry and Madras . 
the mountains in the neighbourhood of Chittoor may be known by 
inspecting the specimens. On these I can only remark, that differ- 
ent parts of the mountains are composed of the different varieties of 
sienite apparently casually, and that the dark rock is in imbedded 
masses. From Chittoor to Arcot, the road in one place passes near a 
mountain which is of the same nature as those of Chittoor, only much 
decayed. White rock is seen on the surface in this stage, and the 
usual rocks here and there jut up above the surface. As we ad- 
vance into the Carnatic from Arcot, there arc no mountains seen to 
the eastward nearer than those of the Mount and Sadros, but 
rocks are seen in many places pushing through the soil, which 
though some of them having veins shew no signs of stratification, 
are of a more vitreous and intimately mixed rock, varying in colour, 
but usually pretty dark. This rock seems to be the chief one in the 
Carnatic, and it is uniform in its composition. 
In order to complete this very imperfect outline of the geology 
of a line drawn from the Malabar coast at Tellicherry eastward to 
Madras, I may observe that the flat form of the Carnatic, that is, of 
all the country east of the eastern Ghauts of Mysore, leads to the 
notion that at some former period this track of country was covered 
by the ocean. In confirmation of this hypothesis are the following 
remarks, which the digging of a well in Colonel Marshall’s garden, 
about two miles from the sea shore at Madras, afforded me the op- 
portunity of making. From the surface for five feet there is a stra- 
tum of brown clay, chiefly intermixed with sand. Then follows a 
stratum of blueish black clay, in which, at the distance of 21 feet, 
there is a thin and scattered layer of large oyster shells which all lie 
in a horizontal position, and into the lamina composing the shell the 
black clay has penetrated, so that they split asunder with great fa- 
cility. There are also shells of the cockle, and other kinds. At the 
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