La Brea Tar Pits

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Three mammoth statues are included in the La Brea Tar Pits.
Three mammoth statues are included in the La Brea Tar Pits.
The Tar Pits in 1910, note the oil derricks in background
The Tar Pits in 1910, note the oil derricks in background
Gas bubble slowly emerging from a smaller tar pit at La Brea Tar Pits.
Gas bubble slowly emerging from a smaller tar pit at La Brea Tar Pits.

The La Brea Tar Pits (or Rancho La Brea Tar Pits) are a famous cluster of tar pits located in Hancock Park in the urban heart of Los Angeles, California, USA. Asphalt (colloquially termed tar) has seeped up from the ground in this area for tens of thousands of years, forming hundreds of sticky pools that trapped animals and plants which happened to enter. Over time, the asphalt fossilized the remains. The result is an incredibly rich collection of fossils dating from the last ice age.

Fossils have been excavated from hundreds of the pits in the park. Work started in the early 20th century. In the 1940s and 1950s there was great public excitement over the dramatic mammal fossils recovered. By the 2000s, attention had shifted to microfossils, to fossilized insects and plants, and even to pollen grains. These fossils help define a picture of what is thought to be a cooler, moister climate present in the Los Angeles basin during the glacial age.

The George C. Page Museum in Hancock Park, part of the Natural History Museum of Los Angeles County, presents these discoveries. Of more than a hundred pits, one (Pit 91) continues to be regularly excavated for two months each summer, under the watchful eyes of tourists[1]. The park's location in a major urban center, the history of dramatic discoveries, and excellent presentation in the Page Museum combine to make the La Brea Tar Pits a famous and accessible paleontological site.

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[edit] Location and formation of the pits

The La Brea Tar Pits and Hancock Park are situated within urban Los Angeles, California, near the Miracle Mile district.

In Hancock Park, asphalt (colloquially termed tar) seeps up from underground. The asphalt is derived from petroleum deposits which originate from underground locations throughout the Los Angeles Basin. The asphalt reaches the surface at several locations in the park, forming pools. Methane gas also seeps up, causing bubbles which makes the asphalt appear to boil. Asphalt and methane also appear under surrounding buildings, requiring special operations to remove, lest it weaken the buildings' foundations.

This seepage has been happening for tens of thousands of years. From time to time, the asphalt would form a pool deep enough to trap animals, and the surface would be covered with a layers of water, dust, and leaves. Animals would wander in and become trapped. They would eventually die. Predators would also enter to eat the trapped animals, and themselves become stuck.

As the bones of the dead animals sank into the asphalt, it fossilised them, turning them a dark brown or black color. Lighter fractions of petroleum evaporated from the asphalt, leaving a more solid substance which held the bones. Apart from the dramatic fossils of large mammals, the asphalt also preserved very small "microfossils", wood and plant remnants, and even pollen grains.

Radiometric dating of preserved wood and bones has given an age of 38,000 years for the oldest known material from the La Brea seeps, and they are still ensnaring organisms today.

[edit] La Brea animals and plants

Saber-toothed cat and giant sloth models on display at the La Brea Tar Pits Museum.
Saber-toothed cat and giant sloth models on display at the La Brea Tar Pits Museum.

Among the prehistoric species associated with the La Brea Tar Pits are mammoths, dire wolves, short-faced bears, ground sloths, and the state fossil of California, the saber-toothed cat, Smilodon californicus. Only one human has ever been found, a partial skeleton of a Native American woman, dated at approximately 9,000 BP ([1]). Much of the early work in identifying species was performed in the early 20th century by John C. Merriam of the University of California.

The park is known for producing myriad mammal fossils dating from the last ice age. While mammal fossils occupy significant interest, other fossils, including fossilized insects and plants, and even pollen grains, are also valued. These fossils help define a picture of what is thought to be a cooler, moister climate present in the Los Angeles basin during the glacial age. Among these fossils are microfossils. Microfossils are retrieved from a matrix of asphalt and sandy clay by washing with a solvent to remove the petroleum, then picking through the remains under a high-powered lens.

La Brea may be the only excavation site in the world where the predators found outnumber prey. Ten predators have been recovered for each prey animal[citation needed]. The reason for this is unknown but one credited theory is that a large prey animal (say, a mastodon) would die naturally or accidentally become entrapped in a tar pit, attracting numerous predators across long distances. This so-called predator trap would kill many animals that found themselves stuck along with their prey. Another theory, specific to the Dire Wolf, suggests that both prey and predators may have been trapped accidentally during the hunt. Since wolves hunt in packs, each prey animal could take several wolves with it.

[edit] Mammals

Below is a partial list of extinct and extant animals with their scientific names included on the right side. This is a selection from the complete catalogue.

[edit] Birds

A partial list of extinct and extant birds found as fossils at La Brea.

[edit] Reptiles, amphibians, and fish

[edit] Invertebrates

[edit] Plants

[edit] Further information

Brea is Spanish for "tar", making "The La Brea Tar Pits" a redundant expression meaning "The The Tar Tar Pits" (an example of pleonasm). The "tar" pits were used as a source of asphalt (for use as low-grade fuel and for waterproofing and insulation) by early settlers of the Los Angeles area. Early settlers mistook the bones in the pits for the remains of unlucky pronghorns or local cattle that had become mired.

Rancho La Brea is the most famous, but there are two other asphalt pits with fossils in southern California: in Carpinteria, Santa Barbara County and McKittrick, in Kern County. There are other fossil-bearing asphalt deposits in Texas, Peru, Trinidad, Iran, Russia and Poland.

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

[edit] La Brea in fiction

Mammoth display models at the La Brea Tar Pits in Los Angeles's Miracle Mile District
Mammoth display models at the La Brea Tar Pits in Los Angeles's Miracle Mile District
  • In the 1997 pseudo-scientific fantasy film Volcano, a volcano grows out of the largest pool of tar (after the mammoth in the diorama sinks into it), spewing a river of hot lava down Wilshire Boulevard.
  • The pits were also featured in the final scene of the movie Miracle Mile, as well as several other movies representative of Los Angeles.
  • In Steven Spielberg's 1979 film 1941, Captain Will Bill Kelso, played by John Belushi, shoots down a plane that he mistook for a Japanese plane into the La Brea Tar Pits.
  • In Last Action Hero, Arnold Schwarzenegger falls into the tarpits and easily wipes himself clean, prompting the kid to point out that he (Arnold) is a character in a movie and not in the 'real' world.
  • The tar pits are also featured in a key scene in "Alan Smithee's" Burn Hollywood Burn.
  • The episode "That's Lobstertainment!" of Futurama depicts an animated version of the tar pits. Fry notices a caveman skeleton with club and wearing an animal skin, causing him to exclaim, "I don't believe it, Sylvester Stallone!"
  • In The Two Jakes a scene takes place at the La Brea Tar Pits.
  • Hidden underneath the museum at the La Brea Tar Pits is the secret base of the heroes of Brian K. Vaughan's comic book Runaways.
  • In My Girl 2, a scene occurs in which Nick pretends to throw Vada's very special ring into the tar pits.
  • In The Simpsons episode "Bart Gets an Elephant", they visit a tar pit attraction modelled on the La Brea Tar Pits.
  • In the novel Mammoth by John Varley, a large part of the plot occurs in and around La Brea in the past and present.
  • In the novel City of Bones by Michael Connelly The tar pits are mentioned in connection with Los Angeles oldest known murder victim who was murdered 9000 years ago.
  • In the 1948 Warner Brothers cartoon "My Bunny Lies Over the Sea," Bugs Bunny is tunneling to Los Angeles intending to visit the La Brea Tar Pits and accidentally winds up in Scotland. [3]
  • In an episode of Kong: The Animated Series, Kong and his human friends go to Los Angeles where they fight the series villain Ramone De La Porta in front of the La Brea Tarpits. The villains use the (non-existent) dinosaur bones in the pits to create monsters which Kong fights.
  • In the ABC sitcom Dinosaurs, which takes place in prehistoric times, there is a reference to the pits in Bob LaBrea, an ancient dinosaur chief, for which the main characters' school, LaBrea High School, is named, despite the fact that no dinosaur bones have been found in the Tar Pits.
  • The Mighty Max series features an episode entitled Tar Wars which is centered around the tar pits.

[edit] See Also

[edit] References

  1. ^ Page Museum. Page Museum - La Brea Tar Pits. Page Museum web site. The Natural History Museum of Los Angeles County Foundation. Retrieved on December 15, 2006.

[edit] External links

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