150 
Records of ike Geological Siirveg of India. 
[voL. XTt. 
quai’tz and gneiss pebbles in a gritty, often senii-lateritio, matrix of reddish purple, 
color, and containing here and there small nests of clay. This conglomerate, 
which is not very hard, rests on the very irregular surface of the banded (slightly 
hornblendic) granite gneiss, to -wliich it has imparted a strong yellow stain. 
Among the more southerly conglomerate beds are those met with in the 
Shenkarai ridge, about eight miles south-by-east of Pudu- 
glomer^e™ ^otai. They are displayed on the western slope opposite 
Shenkarai village by an extensive series of rain gullies 
which expose a considerable surface of the gritty conglomerate; but unfortu¬ 
nately do not cut deeply into it. Its base is not seen, but it probably rests directly 
on the gneiss which shows in Shenkarai tank. The bedding is seen to dip east- 
north-east or east-by-north at angles of from 12° to 15°. False bedding prevails, 
birt only to a small extent, for so coarse a rock. The conglomerate is of mottled 
brown to pinkish and whitish, less frequently reddish-yellow color, and tolerably 
compact with a gritty matrix, including quartz and gneiss shingle, from the size 
of a eocoanut downward, in moderate quantity. The eastern slope of the ridge * 
is overlaid by the most massive and continuous (sheet-like) bed of lateritic con¬ 
glomerate that I have seen on the Coromandel coast; it covers a considerable 
space between Arimullum (Aurmoolum) and Malalapatti, and is itself lost sight 
of to the east under lateritic sands and the alluvium of the VelMr. 
Further eastward, away from the boundary, the conglomeratic character of 
these Cuddalore beds diminishes rapidly, and very few sections are to be found 
that penetrate the surface laterite. Where the sub-rock is reached, it is seen to 
be a grit or sandstone. 
A second section of the Cuddalore beds forming the Shenkarai ridge was 
„ found in the scrub jungle about two miles further south- 
Section near Ayangndi. j. j i x -i ^ _ 
west and about a mile south-east of Ayangudi. The beds 
here seen are unlike the Shenkarai beds, they are conglomerates of very coarse 
texture and rather friable. The matrix, which varies from light red to brown 
red in color, is semi-lateritic and vermicularly cellular to some extent. The en¬ 
closed shingle is mostly large and well rounded; it is chiefly quartzose and all 
apparently of gneissio origin. The lowest bed seen is mottled and more gritty 
in texture with fewer enclosed pebbles. The dip is southerly at low angles. 
Here as at Shenkarai the section penetrates but a few feet vertically. 
A section in which gritty sandstones are seen peeping out below the surface 
„ laterite occurs close to Ammagudi (Aumagoodev') on the 
Section at Ammagndi. , 
left side of the vellar valley, some four miles north-west, 
of Arrantangy. Brown and purple sandstones occur here of sufiicient hardness 
locally to be quarried into coarse flags. They are exposed in the gentle scarp 
below the laterite. 
The last outcrop but one of Cuddalore rocks to be mentioned occurs to the 
south-east of Sivaganga, about a mile and a half from the 
town. Here several beds of hard thick-bedded grit crop 
Section at Sivaganga. 
’ The geographical features of this ridge are very inaccurately shown in sheet 80, where it ap¬ 
pears of considerable height instead of as a mere low rise scarped only for a short distance at its 
northern extremity. Extensive scrub jungle covers the greater part of its surface thickly. 
