1907] Geology Resources of Trinidad and Barbados 79 



pumped from the wells to the height of land whence it descended 

 by gravity to the refining works near the city of Bridgetown. 

 In certain cases the location of the borings was unsuitable, the 

 sediments being too greatly disturbed to be largely productive 

 of oil, so that the yield of petroleum in economic quantity has not 

 been satisfactory; but at other places the conditions are more 

 favourable, the strata being more regular and less broken, while 

 beneath the coral and clay formations, the latter being known 

 under the name of "Oceanic beds," the oil-bearing Tertiary 

 probably occurs througliout the whole extent of the island. 

 Here also, owing to the covering of impervious clays, the pos- 

 sibility of finding oil in paying quantity should be more favour- 

 able than in those portions where the clay and coral formations 

 have been removed, as in the north-eastern portion. The thick- 

 ness of the coral formation varies from a few feet only to 200 feet, 

 and in some places possibly 2 50 feet, and the Tertiary rocks are 

 sometimes seen owing to the denudation of the coral, m^ore 

 especially in the southern and northern portions of tlie island. 

 The judicious expenditure of a certain amount of capital by 

 boring in this coral-capped area should be carefully considerecl. 



In the Oceanic, or clav and earthy deposits, are large beds of 

 infusorial earths, often beautifully white and resembling the 

 infusorial earth obtained from the beds of lakes in eastern Canada. 

 The microscopic examination of the contained foraminifera, 

 however, shews that the forms are of deep sea water types, 

 instead of fresh water origin, as is the case in the northern lake 

 deposits. These infusorial earths should, at some tinie, be of 

 economic importance. No trace of volcanic rocks are seen in this 

 island. 



The manjak deposits of Barbados occur in true fissure veins 

 as in Trinidad, the fissures undoubtedly being formed during the 

 general period of upheaval which affected the Tertiary oil-bearing 

 sands. The origin of this mineral is clearly seen in the case of 

 the shaft referred to where the manjak passed down at 150 feet 

 into petroleum. The inference is that this petroleum has flowed 

 into the fissures thus formed, either from the sides or bottom, 

 from the oil-sands which have been thus traversed ; the volatile 

 matters have been largely removed by oxyd.ation, and the 

 asphaltic portion has remained as a vein filling. Apparently 

 similar conditions affected the albertite deposits of New Bruns- 

 w^ick. 





