Tar pit

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Tierra La Brea, Trinidad

A tar pit, or more accurately known as an asphalt pit or asphalt lake, is a geological occurrence 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[edit]

La Brea Tar Pits, California

There are only a few known asphalt lakes worldwide:

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

For other rich deposits, fossilized where they occurred, see Lagerstätten. Tar pits are the resting places of many fossils.

Paleontological significance[edit]

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 find it impossible to free themselves before they die of starvation, exhaustion from trying to escape or from the heat that would come from the sun. Over one million fossils have been found in tar pits around the globe.[4]

Living organisms[edit]

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

See also[edit]

References[edit]

  1. ^ [1], Geological Society of Trinidad and Tobago (GSTT), principle for an asphalt lake, accessdate=2010-08-28
  2. ^ [2], The Suburban Emergency Management Project (SEMP), Asphalt Lakes, accessdate=2010-08-28
  3. ^ Perkins, Sid. "South America's sticky tar pits". Retrieved 2012-05-05. 
  4. ^ Perkins, Sid. "South America's sticky tar pits". Retrieved 4 May 2012. 
  5. ^ "Bubble, bubble, oil and...bacteria!". Retrieved 4 May 2012.