116 ROYAL SOCIETY OF CANADA 
rocks of Tertiary age, similar in character to those of Trinidad was 
established. These were also found to contain petroleum and the 
asphaltic mineral Manjak, the former in apparently large quantities. 
Prior to the last eight or ten years but little in the way of develop- 
ment of these minerals had been attempted. For nearly a quarter of a 
century the great value of the remarkable deposit of asphalt at the Pitch 
Lake on the west coast near Point la Brea was known and a large 
business had been carried on at this place in the mining and shipment 
of this material in both the raw and boiled condition. Near the town of 
San Fernando also on the west coast, other asphaltic deposits known by 
the name of Manjak, were discovered some years ago and have been 
worked in a desultory way. The oil-bearing nature of certain areas in 
the southern portion of the island was inferred from the occurrence at 
various points of deposits of asphalt and of oil-springs, and a well was 
sunk, a short distance south of the Pitch Lake to a short distance but 
never finished. From this well, however, though largely choked with 
debris, crude petroleum has been issuing for a quarter of a century in 
small quantities. It was allowed to run to waste till quite recently, 
though within the last year this waste has been stopped and the crude 
material is now collected. Some half dozen years ago attempts were 
instituted to obtain the oil in quantity elsewhere by a regular system of 
borings which have been successful in finding petroleum in large amount. 
The inception of this scheme is largely due to Mr. Randolph Rust, of 
Port of Spain, whose faith in this industry has never flagged. 
Generally speaking, the geological structure of the island is some- 
what simple. Along the north coast from the passage, known as the 
Bocas, which separates the north-west corner from Venezuela, a range of 
hills with elevations from 2,000 to more than 3,000 feet above the sea, 
extends continuously to the north east corner. The rocks of this range 
are mostly slaty, comprising a considerable thickness of crystalline 
schists, in large part a true quartz-mica schist. With these are asso- 
ciated considerable areas of limestone, more especially in the western 
part. The schists are intersected by numerous veins of quartz, the 
greater part observed being short and gashy, but in places well-defined 
quartz leads occur. In this quartz the presence of gold has been detected 
in small quantities, and indications of iron ores have been recognized. 
So far, however, but little attempt has been made to ascertain the value 
of the rocks of this range as a source of mineral wealth, the work of the 
geologist being confined for the most part to the study of the oil-bearing 
rocks of the southern portion. The formation as a whole is eminently 
worthy of a careful examination along these lines. 
