SUB-RECENT MARINE BEDS. 61 



various degree of coarseness, tlie finer beds being generally the richest 

 in fossils, which are all of living species. Except when exposed by 

 weather action, the fossils are difficult to extract in recognisable condi- 

 tion owing to the hardness of the matrix. The gritty beds show a good 

 deal of false bedding locally, and the beds exposed on the eastern side of 

 the estuary have in one place a strong easterly dip as if they had been 

 uptilted, but this only extends for a short distance and may have been 

 due to the action of a strong local current prevailing at the time of 

 deposition. Only a narrow strip of the marine beds is exposed on either 

 side of the river and southward for about half a mile along the coast. 

 A teri hides the western extension of the beds on the western side of 

 the estuary, and the western ends of the coast dune and a parallel teri do 

 the same for the shelly beds east of the estuary. I was first introduced 

 to this interesting patch of marine beds by the Right Reverend Bishop 

 (then Dr.) Caldwell in 1869, when I devoted several hours to collecting 

 the fossil shells, which had all to be chiselled out of the hard rock. On 

 the occasion of my second visit in 1882, I found that the teri and dune 

 sands had covered up much of the sandstone surface before exposed. 

 The fossils obtained from the Nambi-Ar beds were as follows : — 



Cyprsea Arabica. 



„ sp. 

 Conus puuctatus ? 

 Purpura persica. 

 Turbo, sp. 

 Trochus, sp. 



Ceritbium, sp. 

 Ostrea, sp. 

 Area granosa. 

 Cardium, sp. 

 Cytberea, sp. 



In the section near the bank of the Yellava Odai (an affluent of 

 the Nambi-Ar), described at page 41, is a bed of 



Yellava Odai section. i i t • 



calcareous clayey sand abounding in marine and 

 estuarine shells of living species resting upon, and in one place distinctly 

 intercalated between white gritty sandstones of typical Cuddalore aspect. 

 The grit is nowhere seen to be fossiliferous. The patch of marine beds 

 is but ill-exposed owing to a thick covering of sandy soil. It is only in 

 the south bank of the Yellava Odai and in the banks of a rain-gully 

 opening into it that the beds are exposed continuously for a few 



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