Tar pit

Tierra La Brea, Trinidad

A tar pit, or more accurately known as an asphalt pit or asphalt lake, is a type of petroleum seep where subterranean bitumen leaks to the surface, creating a large area of natural asphalt.^[1][2] This happens because, after the material reaches the surface, its lighter components vaporize, leaving only the thick asphalt.^[3]

Known tar pits

La Brea Tar Pits, California

There are only a few known large asphalt lakes worldwide:

• Pitch Lake at La Brea, Trinidad and Tobago
• Lake Bermudez at Libertador, Estado Sucre, Venezuela
• La Brea Tar Pits in Los Angeles, California, US
• McKittrick Tar Pits at McKittrick near Bakersfield, California, US
• Carpinteria Tar Pits at Carpinteria, Santa Barbara County, California, US
• Tar pits near Hīt, Iraq
• Binagadi asphalt lake in Baku, Azerbaijan

Note that even being in Anglophone countries, some placenames of tar pits in Trinidad and California come from the noun brea, Spanish for "tar".

There are other fossil-bearing asphalt deposits in Oklahoma, Texas, Peru, Trinidad, Iran, Russia and Poland.

Paleontological significance

Animals are usually unable to escape from the asphalt when they fall in, making these pits excellent locations to excavate bones of prehistoric animals. The tar pits can trap animals because the asphalt that seeps up from underground forms a bitumen pit so thick that even mammoths found it impossible to free themselves before they die of starvation, exhaustion from trying to escape, or from exposure to the sun's heat. Over one million fossils have been found in tar pits around the globe.^[3]

For other rich deposits, fossilized where they occurred, see Lagerstätten.

Living organisms

Living bacteria have been found in the La Brea Tar Pits. These organisms have been shown to be strains of previously discovered bacteria. They have been able to survive and thrive in an environment with no water and little to no oxygen. Scientists started looking for the bacteria when they noticed bubbles of methane coming out of the tar pits.^[4]

Other microorganisms have been found living in microliter-sized droplets of water recovered from Pitch Lake in Trinidad, including bacteria from the orders Burkholderiales and Enterobacteriales. ^[5]

Helaeomyia petrolei, the petroleum fly, spends its larval stage within the tar pit itself.

See also

• Petroleum seep
• The Mythical Man Month, where a tar pit is used as an analogy to describe Brook's Law.
• formerly Lake Asphaltitis for the Dead Sea (coined by Titus Flavius Josephus)

References