154 
Records of the Geological Survey of India. 
[vOL. XII, 
rougher duller surface with many fewer vermicular cavities. The larger enclosed 
fragments of older rocks, which consist almost entirely of gneissic quartz, are 
mostly suhangular or angular, giving the rock a breccia-like appearance. Well- 
rounded pebbles do, however, also occur. A conspicuous example of such a 
breccia-conglomerate is that occurring to the west of Payakudi in the north¬ 
western corner of the Tanjore patch. 
The outlying patches of laterite conglomerate I’esting on the gneiss in the 
northern part of our area agree generally in character with the gritty variety 
just described, but those in the south-westerly part are of the more typical 
form with many vermicular cavities in the more clayey mass. The southern 
patches when very conglomeratic contain chiefly well-rounded water-worn pebbles, 
and approach in coarseness to some of the typical conglomerates of median 
texture in the Madras region, in which stone implements occur. Whether stone 
implements occur in this southern laterite is a question to which a positive 
answer cannot yet be given, no unquestionable examples having as yet been 
found. I did, however, find occasional specimens of coarse quartzose stone 
which bore a resemblance in shape to various forms of chipped implements 
common in the more northerly gravels and conglomerates, but the material is so 
coarse that the chipping could not be considered as positively artificial. The 
most undoubtedly artificial specimen was a broad axe-head found about a mile 
north-north-west of Shuragudi in the Shahkotai patch. Occasional fragments 
of chert derived from unknown sources occur scattered spai’sely over the surface 
of the lateritic conglomerates. Throe specimens of this chert appear to be of 
artificial shape, one is a flake of small size resembling an arrow-head, the second 
a small prismatic core, the third a thick oblong sharp-edged flake with a distinctly 
serrated edge to one of its longer sides. 
Several large leaf-shaped flakes, almost deserving to be called implements, 
were found by me between Vellam and Tanjore, only a little distance north of 
the line forming the northern limits of sheet 80. Two of these were adherent 
to the surface of the conglomerate and appeared to be genuine exposures in situ. 
They had to be hammered out of the rock. 
These large flakes appear to be made of a chert identical with that forming 
the great fossiliferous blocks lying in the mottled grits occurring to the east of 
the old fort ditch at Vellam. ^ The small implements above mentioned are made 
of a much more jaspery-looking variety of chert. 
I cannot help thinking that closer search of the shingly lateritic beds such 
as that at Tallakolum (Tullahcolum), north of Madura, and those occupying so 
large a part of the two Tripatur patches, would lead to the finding of unques¬ 
tionably recognizable specimens of chipped implements. 
Of the very numerous spreads of lateritic gravelly sands which occupy the 
eastern part of the lateritic area, the most remarkable is that cut through by 
the P.4mani river at and to the south of Manargudi in Tanjore district, which 
also extends close down to the sea-coast at Adrampatam. 
’ See Mem. G. S. I., IV, p. 36. A fresh collection of fossils from these chert rocks was made 
in 1878 to supply, as far as possible, the place of the collection lost on its way to Calcutta by the 
wreck of the Aurora in 1860. 
