162 CRETACEOUS EOCKS OF S. INDIA. [PaRT II. § 2. 



few points indeed, is the base of the Arrialoor group already marked by- 

 its fossil contents, viz., to the North-east of Koloture, in the nullah to 

 the South of Kurribiem, and in the two nullahs to the East and North of 

 Veraghoor. In most of these cases, however, the sections are not 

 clear enough to enable one to examine the actual junction of the beds 

 in section, and it may be that a slight unconformity exists, which I 

 have been unable to detect. In the nullah to the East of Veraghoor an 

 unconformity is indeed indicated by the diiference of dip, that of the 

 Trichinopoly beds being from 6° to 8°, while the lowest beds of the 

 Arrialoor appeared to dip at 3° only; but the beds are only exposed in 

 the bed of the nullah, and being waterworn, no great dependance could 

 be placed on this observation. A short distance beyond the dip was 

 clearly ascertainable, and as much as 6°, or about the same as that of 

 Trichinopoly group. I am inclined to believe that were the beds further 



North, near the final overlap of the Trichinopoly 

 Unconformity of groups. r» • i • -i 



group, better seen, the uncontormity which pro- 

 bably exists would be more clearly established, as the narrowing 

 of the Trichinopoly out-crop in this direction is much more rapid 

 than can be reasonably accounted for by the thinning out of the deposits, 

 and must be due to the Trichinopoly group being gradually overlap- 

 ped. The same thing probably takes place as far South as the deposits 

 are distinctly bedded, the fact not being ascertainable, owing to the 

 obscurity of the Geological features. 



The Arrialoor group overlaps the Trichinopoly group at both 

 extremities. If, therefore, there were no denudation of the latter in 

 the interval of their formation, the Arrialoor period was simply one of 



further depression, and of extension of the sea 



Conditions of interval. ^ , ... ., i ■ t . ii ,, 



area, and the preceding interval, indicatecl by the 



change of the fauna, may have been simply one of statical conditions 



during which no deposit took place in the area now exposed by 



denudation. 



