ON THE GEOLOGY OF BIRBADOS. 



219 



The following are analyses of three of the Trinidad sample; 



Philippine Estate. Hermitage. Cedar Grove. 



Combined water 



Crystalline silica, &J 



Colloid silica 



Clay 



Iron peroxidf* and alumina 



Manganese peroxide 



Calcium carbonate 



Calcium sulphate 



Calcium phosphate 



Lime 



Magnesia 



Alkalies 



2-38 



4-62 



2-11 



l-b'8 



4-05 



147 



19-65 



41-15 



41-56 



26 38 



15-36 



15-16 



5-64 



3-31 



4-10 



■32 



•44 



•82 



40-50 



29-46 



31-82 



•18 



•09 



•28 



trace 



trace 



trace 



1-22 



111 



l-oO 



2-34 



•41 



1-18 



traces 



traces 



trac?s 



10000 



100-00 



10000 



(b) Hai/fi — Slides of washed radiolarian earth purporting to come 

 from Port Jeremie in Hayti are on sale by European dealers. We 

 have procured (and examined) several such slides from different 

 persons, and find them all similar to one another and much re- 

 sembling similarly prepared material from Barbados, but we cannot 

 obtain information regarding the deposit from which they have been 

 procured. 



(c) Jamaica. — The White Limestone of Jamaica has been men- 

 tioned in the first part of this memoir, and some reasons were given 

 for thinking that it is not a single formation as represented in the 

 Reports of the Geological Surveyors (1869),'^ but comprises at least 

 two limestones of different origin and age. 



The descriptions of the Surveyors generally recognize two divisions 

 in the White Limestone : a lower portion consisting of bedded 

 limestones interstratified with marls, and an upper series of more 

 massive limestones. The lower beds often contain nodules of flint, 

 while the upper do not ; on the other hand remains of moUusca, 

 corals, and echinoderms appear to be more abundant in the upper 

 beds. It should have been stated that the S])ecimens of limestone 

 from the counties of Manchester and St. Elizabeth which were 

 examined by Mr. W. Hill and found to resemble coral-limestones were 

 from the upper beds ; while the rock obtained by Col. Eeilden from 

 Hanover County was almost certainly from the lower beds, inas- 

 much as he informs us that flints were abundant in it. This rock 

 is identified by Mr. Hill as an oceanic limestone similar to the 

 calcareous earths of Barbados, but altered and indurated by cal- 

 cification. The flints are said to resemble those from the English 

 Chalk. 



With respect to the ago of the White Limestone the reports of 

 the Surveyors are inconsistent with one another ; in some (as on 

 pp. 23 and 149) it is spoken of as Miocene, in others as Pliocene 

 (pp. 129, 301), and in the Tabular View at the end of the volume it 



^ ' Eeport en the Geology of Jamaica,' by Messrs. Sawkina, Barrett, and others, 

 Mem. Greol. Survey, 1869. 



