PAUT 3.] Foote: Geological features of the Madura District, ^-c. 
151 
out from below the general lateritic covering of the country. In color the rock is 
dark purplish-grey with brown bandings, and so hard as to be worked by blasting 
The beds have a north-easterly dip of about 20°. Much diagonal or “ false ” 
bedding is seen in the fresh broken specimens of the rock, which is overlaid con¬ 
formably to the eastward by less compact dark-brown and yellow-brown grits. 
The hard grits are largely quarried as building stones. Unfortunately no 
laterite is seen in juxtaposition with the grits, so the local stratigraphical rela¬ 
tions of the two rocks cannot be studied. 
The best section of Cuddalore grits of the softer variety occurs about eleven 
miles north-east fi’om Pudukotai, a little west of the high 
Section at Perungalur. Tanjore. Here the small stream which feeds the 
Perungalur tank, in descending fi'om the high ground to the north, cuts through 
the upper laterite beds, and exposes beds of typical grits in many gullies, forming 
so many miniature canons of very perfect shape with nearly vertical sides, from 
12 to 18 feet deep and only 2 or 3 feet apart at the bottom. The grit beds show a 
rude but distinctly columnar jointing strongly resembling starchy cleavage on 
a huge scale. 
The section here displayed shows the following sequence of beds in descending 
order:— 
4. Black laterite conglomerate, on gravel. 
3. Bed-brown vermicularly porous conglomerate, passing down into 
2. Brown conglomerate with many pebbles of quartz-grit and older laterite. 
1. Grits, pale mottled, generally showing columnar jointing with vermicular tubes and 
scattered galls of fine clay. 
In this section distinct unconformity is seen to exist between Nos. 1 and 2. 
No signs of organic remains could be traced after very careful search. 
A small show of rather soft giit of red and brownish mottled color appears 
between the boundary of the gneiss and the overlying laterite between Surian- 
patti (Pothanavial of the Atlas map) and Parembur in the south-western corner 
of the Tanjore patch. 
Mottled grits which on petrological grounds are considered as of Cuddalore 
age are exposed, in sections of wells and deep tanks, under the laterite conglome¬ 
rate at Palatur (Pullatoor) and Shuragudi (Shooragoody) in the Shahkotai 
patch of the lateritic formations (see page 153). 
The boulder beds described above (page 148) as occurring to the north-east of 
Sivaganga may possibly be of Cuddalore age, or tertiary, 
Age of boulder beds. instead of Eajmahal age, or secondary, as there is no 
positive evidence either from the presence of organic remains or speciality of 
stratigraphical position, but in their facies they are decidedly much more akin to 
the older series. 
V.— The Lateritic Group. 
The Cuddalore series is overlaid by the several members of the lateritic 
series, which vary from hard typical conglomerates through gritty beds to gravels 
and finally to reddish sands with variable quantities of gravelly pisolitic hsematite 
