The Pitch Lake is the largest natural deposit of asphalt in the world, located at La Brea in southwest Trinidad. It has fascinated explorers, scientists and the common folk since its discovery by Sir Walter Raleigh in the year 1595. Raleigh himself found immediate use for the asphalt to caulk his ship. Since then, there have been numerous research investigations into the use and chemical composition of this material. Above all, there have been countless theories, postulations and conclusions as to the size, source and origin of the asphalt. The lake covers about 40 ha and is reported to be 75 m deep. The Pitch Lake is a tourist attraction that attracts about 20,000 visitors annually. It is also mined for asphalt which is exported for high-quality road construction.
The origin of Pitch Lake is related to deep faults in connection with subduction under the Caribbean Plate related to Barbados Arc. The lake has not been studied extensively, but it is believed that the lake is at the intersection of two faults, which allows oil from a deep deposit to be forced up. The lighter elements in the oil evaporated, leaving behind the heavier asphalt. Bacterial action on the asphalt at low pressures creates petroleum in asphalt.
The Chaima Indians had other ideas about how the lake was formed. After a victory over a rival tribe, the tribe got carried away with its celebration, cooking and eating the sacred hummingbirds they believed held the spirits of their ancestors. Thus, legend has it, their winged god opened up the earth and conjured up a lake of nasty pitch to swallow the entire village. Amerindian pottery has been found, along with the remains of prehistoric animals such as the mammoth and what is believed to be the tooth of a giant sloth.
Pitch Lake is one of several natural asphalt lakes in the world, others being the La Brea Tar Pits, and the one at McKittrick, both in the US State of California; and the Republic of Venezuela’s Lake Guanoco.