[ELLs] NOTES ON GEOLOGY OF'TRINIDAD AND BARBADOS 129 
issuing from the sides of gullys along streams or in out-flows of asphalt 
over the surface, and also in the form of Manjak which occurs 
in veins similar to those in the mines near San Fernando in Trinidad. 
While the exposed area of these oil-bearing rocks is comparatively 
small, it seems reasonable to suppose from the general strike of the strata 
in the exposed portions and of the isolated outcrops elsewhere, that they 
underlie the coral and Oceanic deposits throughout the entire island. 
As in Trinidad the problem of finding petroleum in large quantities 
is one of great importance to the inhabitants. While the sandstones 
are in places completely saturated with the oil so that in places it is 
constantly oozing from the surface, over much of the exposed area of 
these rocks they are so intricately folded and contorted as to apparently’ 
render the finding of petroleum in economic quantities very problema- 
tical. In certain places, however, considerable areas occur in which the 
foldings are more regular, and the faulting small, while the possibilities 
of finding oil by boring through the overlying Coral formation or the 
Oceanic clays into the underlying Tertiary sandstone beneath, is well 
worthy of careful consideration. 
The Manjak deposits which here occur have been formed in the same 
way of those of Trinidad, in fissures in the sandstone and shale developed 
in the process of rock folding. They occur along the sides of the 
anticlines, generally near the crests, and have been mined at several 
points with an output amounting to several thousands of tons. As 
already noted, at one of these shafts, sunk toa depth of 150 feet in what 
is called the Vale district near the eastern portion of the Tertiary out- 
crop, the mineral, which was of a high degree of purity, gradually became 
softer and finally passed into the condition of liquid oil, rendering 
further mining impossible. From this shaft the liquid oil, black and 
very asphaltic, is now being removed by baling at a rate of half a barrel 
per day the output being regarded as of special value as a lubricating 
oil. From this there is a fair conclusion that the manjak has been 
derived from the crude petroleum, from which the volatile matters have 
been evaporated. The veins where elsewhere opened show the same ten- 
dencies as in Trinidad and in New Brunswick, to vary in thickness, the 
width of the vein increasing very materially and rapidly at times and 
then diminishing, owing apparently to a lateral displacement of the sides 
of the fissure, but the evidence of their vein like nature is quite clear. 
Some of the borings for oil have reached depths of over 1,200 feet, 
though it does not appear that the formation has anywhere been entirely 
penetrated ; but from the highly inclined condition of much of the strata 
where such borings have been made such holes can hardly be regarded 
as giving much reliable information as to the actual thickness of this 
