138 



Bulletin 35 



286 



fore. Hill's observation that Orbitoides are not found above the 

 Eocene is, in my opinion fully borne out by the facts here as well 

 as in Jamaica. 



I consider that the rocks occurring in the Marbela Mine 

 down to the depth of 160 feet represent the Nariva series, while 

 the lower beds represent the Naparima oceanic deposits. These 

 last differ in some respects from the Naparima oceanic beds, and 

 the difference may be due to the deposition of the sediments in a 

 shallower sea on the flanks of the cretaceous ridge crossing the 

 middle of the Island and lying to the north of the great Naparima 

 Anticline. In my first note already quoted I described the differ- 

 ence in these words : ' 'A very noticeable difference is that the 

 material of the oceanic beds when washed yields a residue con- 

 sisting almost entirely of Foraminifera (chiefly globigerina), 

 while that of the Marbela deposit consists of small pieces of slaty- 

 looking and ferruginous materials, the foraminiferal fauna 

 being much scantier than that of the oceanic beds." While 

 admitting a large amount of variation in composition in the 



Page 54 



Naparima rocks, this may be held to be true generally of the 

 oceanic beds. We have to assume therefore a shallower sea and 

 a greater quantity of muddy sediment in this area than in that to 

 the south of Naparima Hill. {See my Section in Journal of the 

 Geological Society, 1892, p. 522). 



From Mr. Wilson I received some additional samples of a 

 hard sandstone which appear to have come from a lower depth 

 than the Orbitoides bed, some 220 feet deep. These contain fos- 

 sils but not in a determinable condition, and the rock is so hard 

 that there is no means of extracting them. I believe, however, 

 that these rocks are the very base of the tertiaries or top of the 

 cretaceous. I consider therefore, that the rocks at the Marbela 

 Mine represent the equivalent in time of the whole Naparima 

 series and extend downwards from the Miocene inclusive to the 

 Eocene and top of the cretaceous. They were however deposited 



