TEETIARr MICROZOIC FOEMATIONS OF TRINIDAD. 525 



and 17 (Glohigerina, &c.), and then the section is terminated on the 

 south and west by the swamps and mud-flats of the Oropuch Lagoon, 

 beneath which lies the extension of the radiolarian marls of South 

 Naparima. 



Mr. Louis de Yerteuil, the manager of Mr. Lamont's sugar plan- 

 tations in South Naparima, very kindly gave me his assistance in 

 examining the rocks of that district. He accompanied me to the 

 several excavations and cuttings made in the marls for railway and 

 agricultural purposes. From these in several instances I obtained 

 evidence of the dip and strike of the rocks : and I believe there is 

 little doubt that the radiolarian beds are thrown down below the 

 Oropuch Lagoon and thus do not appear in the coast-section. No 

 clear case of the junction of these beds with the foraminiferal beds 

 has been observed, and I think, for reasons I will now state, that 

 it is unlikely — save under exceptional conditions — that any such 

 case will be found. 



The faults marked in the diagram (p. 522) are inserted, generally 

 speaking, from inference only. The nature and constitution of the 

 JS'aparima rocks (as will be described in the course of this paper) 

 are such that wherever a fault occurs the adjacent rock is shattered 

 and broken up and thus easily disintegrated and removed. A ravine 

 or valley is almost always the result. The rivers or creeks called 

 Taruba, Sipero, and Ally are each probably caused by two or three 

 contiguous faults. Wherever these or similar ravines come out on 

 the coast-line they are worn down by denudation below high-water 

 level and thus pass into the state of tidal swamps. Consequently 

 no section is visible. 



§ 3. PhTSICAL AISTD OTHER CHARACTERS OF SOME OP THE 



Naparima Microzoic Eocks. 



The following analyses of the argiline of Naparima Hill and 

 of the white (radiolarian) marl of South JN'aparima are given at 

 page 132 of the Geological Eeport on Trinidad : — 



Argiline, White Marl, 



Hygroscopic Water 2-00 I'SO 



Combined Water and Organic Matter 4-50 7'50 



Soluble in Acid. 



Silica 0-39^ r 0-62^ 



Oxide of Iron, &c 8-80 I ^±.^a ] ^'SOJoj^-^ 



Carbonate of Lime 3-75 (- ^^ ^'^ 1 18-65 M" ' ^ 



Carbonate of Magnesia 1-22 J [ 1-20 J 



Insoluble. 



Silica 68-001 r57-9n 



Alumina, &c 8-54 1... 77-86 J 4-28 | gg.-^g 



Lime 1-32J j 0-72 [ 



Magnesia 115 [ 5-25J 



Loss '13 



100,23 

 2o 2 



