SUB-RECENT MARINE BEDS. 55 



the small laterite tract of Tripatur (see page 47), in the non-ferru- 

 ginous parts of which the pebbles are greatly bleached and much mixed 

 with a whitish clayey grit. Allowance has, of course, to be made in 

 contrasting these formations for the different character of the rock 

 forming them. In the case of the Conjeveram beds the gravel consists 

 most largely of hard quartzite derived directly, or indirectly, from the 

 vast quartzite beds of the Kadapa series, while the southern shingle 

 beds are made up of rolled pieces of the granular quartz rock which 

 plays so important a part in the metamorphic country south of Trichi- 

 nopoly. 



CHAPTER VII. 



THE SUB-RECENT MARINE BEDS. 



A very interesting series of marine rocks, generally more or less 

 calcareous grits, forms a narrow and rather broken fringe along the 

 coast from Cape Comorin to the Pamban (Paumben) channel. These 

 beds can in great part be regarded only as the ruins of a once far more 

 widely extended formation, by far the greater portion of which has been 

 removed by denudation. Here and there outliers and patches of these 

 beds have been left, which testify to the fact that since their formation 

 under the sea the country must have undergone an elevation of close 

 upon 300 feet, if not more; others of the marine beds, however, have 

 been upraised to a very much smaller extent, or were, what seems even 

 more probable, deposited at a later period while the elevatory action 

 was still in progress. Despite this very great difference in the level of 

 the several marine formations belonging to this group, it was found 

 impossible to assign them to more than one group, and as far as my ex- 

 amination of these two stages of marine formations and their organic 

 contents went, I was unable to perceive any biological grounds for 

 their separation, for both contain only species such as are now found 

 living in the adjoining sea. 



In describing the several patches of this marine group, it will be 



( 55 > 



