Pitch Lake, Trinidad - The Largest Natural Deposit of Asphalt
The Pitch Lake is located in southwest Trinidad in the village
of La Brea. It’s the largest and most significant pitch lake in the
world, measuring approximately one hundred acres (41 hectares), and is
estimated to be 76 meters deep in the center. The liquid asphalt is
black and viscous, but the surface is semisolid, and can be walked on.
The asphalt is so soft in some areas that an individual can slowly sink
if he or she stands on the surface too long. In some places one can put a
stick through the asphalt and remove liquid tar. Although the lake
appears quiescent the asphalt still moves with a natural slow "stirring"
action. Not only can the flow lines be seen on the surface of the
asphalt, but prehistoric trees and other objects have been known in the
past to have appeared, disappeared and reappeared.
The lake was
created thousands of years ago by the process of subduction, when the
Caribbean continental plate was forced under another plate. This opened
fault lines that allowed oil from deep underground deposits to rise to
the surface, where it collected in a volcanic crater. The air caused
lighter elements of the oil to evaporate, leaving behind the heavy
asphalt, a mix of oil, clay and water.
When
Sir Walter Raleigh discovered the Pitch Lake in 1595, it was already
known as the Tierra de Brea, it's Spanish name, by the Amerindians
guides who introduced Sir Walter to the 100-acre lake of black gold. Sir
Walter Raleigh immediately recognized the potential and began caulking
his ships with the tar. On his second voyage to Trinidad, Sir Walter
Raleigh took some of the asphalt home with him, where it was used to
pave Westminster Bridge for the opening of Parliament. Unfortunately the
raw pitch melted in the sun, as it has a tendency to do, covering
horses hooves and gumming up carriage wheels.
Mining of the lake
started in 1867, and an estimated 10 million tons of asphalt has been
extracted since. Tar from the La Brea Pitch Lake in Trinidad has been
used to provide high grade road surfaces not only in Trinidad, Tobago
and the other islands of the Caribbean, but it has also paved streets in
over 50 countries including the United States of America, England,
India, Singapore, Egypt, and even Japan. The lake is estimated to
contain reserves of around 6 million tons, which would last 400 years at
the current rate of extraction.
The La Brea Pitch Lake attracts
about 20,000 visitors annually. People occasionally swim in the waters
of the pitch lake which some say is therapeutic because of the sulphur
content.
Apart from being a natural wonder, the lake has great
social and economic value to residents of La Brea in particular and
citizens of Trinidad and Tobago. However, its benefit is far reaching,
including both to the Caribbean community and to other countries of the
world.
