The La Brea Tar Pits is a group of tar holes where Hancock Park was formed in urban Los Angeles. Natural asphaltum (also called asphaltum, bitumen, pitch or tar - brea in Spanish) has been seeping from the ground in this area for tens of thousands of years. Ter often covered with dust, leaves, or water. Over the centuries, the ter preserves the bones of trapped animals. The George C. Page Museum is dedicated to researching tar holes and displaying specimens from dead animals there. The La Brea Tar Pits is a National Landmark registered landmark.
Video La Brea Tar Pits
Formation Edit
Tar pits consist of a heavy oil fraction called gilsonite, which seeps from the Earth as oil. At Hancock Park, crude oil seeps along the 6th Street Fault of Salt Lake Oil Field, which underlies most of Fairfax District to the north of the park. The oil reaches the surface and forms a pool at several locations in the garden, becoming asphalt as a lighter fraction of petroleum or vapor biodegradation.
The tarred pits seen today are actually derived from human excavations. The hole of the lake was originally an asphalt mine. Other holes seen today were produced between 1913 and 1915, when more than 100 holes were dug to search for large mammalian bones. Various combinations of asphaltum and waggler have since filled these holes. Usually, the asphalt appears in the vent, hardened on exit, forming a stubby mound. This can be seen in some areas of the park.
This seepage has occurred for tens of thousands of years. From time to time, the asphalt will form a thick enough deposit to trap the animal, and its surface will be covered with a layer of water, dust, or leaves. Animals will wander, get trapped, and eventually die. Predators will go in to feed on trapped animals and also become stuck. When the dead animal bone sinks into the asphalt, it seeps into it, turning it into a dark-brown or black color. Lighter petroleum fractions evaporate from asphalt, leaving a denser, bone-packed substance. The dramatic fossils of large mammals have been removed from the tar, but the asphalt also protects the microfossils: the remains of wood and plants, rodent bones, insects, molluscs, dust, seeds, leaves, and even pollen. Examples of some of them are on display at the George C. Page museum. The radiometric dosage of wood and bone preserved has given the age of 38,000 years for the oldest known material from La Brea seepage. Pit still traps organisms today, so most holes are lined up to protect humans and animals.
Maps La Brea Tar Pits
History Edit
The Chumash and Tongva Native Americans living in the area made a boat different from the others in North America before being contacted by the settlers. Drawing down the fall of California redwoods and driftwood pieces from the Santa Barbara Channel, their ancestors learned to close the gap between large wooden planks using tar's natural resources. This innovative form of transport allows access up and down to the coastline and to the Channel Islands.
The Portolà Eksp expedition, a group of Spanish explorers led by Gaspar de PortolÃÆ'¡, made the first written record of the tar holes in 1769. Father Juan CrespÃÆ' wrote,
While crossing the valley, the scouts reported seeing some tar geysers coming out of the ground like springs; it boils liquid, and water flows to one side and tar to the other. The scouts report that they have found many of these springs and have seen the great swamps among them, enough, they say, to take many ships. We are not so lucky ourselves to see these geysers, even though we expect them; because some distance from the way we took, the Governor [PortolÃÆ'¡] did not want us to pass them. We baptize them Los Volcanes de Brea [Tar Volcano].
Harrison Rogers, who accompanied Jedediah Smith on his 1826 expedition to California, was shown a piece of asphalt compacted while in Mission San Gabriel, and noted in his journal that "Citizens use it very well to coat their roofs."
The La Brea Tar Pits and Hancock Park are located in what was once a Mexican land-giving Rancho La Brea, now part of the urban Los Angeles district of Miracle Mile. For several years, tar-covered bones were found on the Rancho La Brea property but were not originally recognized as fossils because farms have lost a variety of animals - including horses, cows, dogs, and even camels - whose bones are very similar to some fossils. type. Grant of the original Rancho La Brea land establishes that tar pits are open to the public for the use of local Pueblo. Initially, they thought the bones in the pits for the remains of pronghorn preluks ( Antilocapra americana ) or cattle that had become mired.
Union Oil geologist W. W. Orcutt, in 1901, with the first recognition that preserved prehistoric animal bone fossils were stored in asphalt pools at Hancock Ranch. In order to commemorate Orcutt's early discoveries, paleontologists named the La Brea coyote ( Canis latrans orcutti ) in his honor.
Scientific resources Edit
Contemporary bone-digging began in 1913-1915. In the 1940s and 1950s, public exuberance was generated by the preparation of large mammal bones that had previously recovered. Subsequent studies have shown that vertebrate fossil material is well preserved, with little evidence of bacterial degradation of bone protein. They are believed to be from the last glacial period, believed to be around 30,000 years ago. After radiocarbon dating shortens the last glacial period because it still occurs 11 to 12,000 years ago, the fossils were diredasi into 10-20,000 years.
Bacteria Edit
Methane gas escapes from tarholes, causing bubbles that make asphalt seem to boil. Asphalt and methane appear beneath the surrounding buildings and require special operations for removal to prevent the weakening of the foundation of the building. In 2007, researchers from UC Riverside found that the bubbles were caused by hardy forms of bacteria embedded in natural asphalt. After consuming oil, bacteria release methane. About 200 to 300 new species of bacteria are found here.
George C. Page Museum Edit
The George C. Page Museum of La Brea Discoveries, part of the Los Angeles County Museum of Natural History, was built beside the tar holes at Hancock Park on Wilshire Boulevard. Construction began in 1975, and the museum opened to the public in 1977.
However, the history of the fossil museum actually began in 1913 when George Allan Hancock, owner of Rancho La Brea, granted exclusive excavation rights to the Los Angeles County History Museum in Tar Pits for two years. In two years the Museum was able to extract 750,000 specimens at 96 sites which ensured that a large number of fossils would remain consolidated and available to the public. Then in 1924, Hancock donated 23 acres to LA County provided that the county provides for the preservation of the park and fossil exhibits found there.
The museum tells the tale pits and presents the specimens excavated from them. Visitors can walk around the park and see tar holes. In the garden yard is a model of prehistoric animal size in or near the tar hole. Over 100 holes, only Pit 91 is still unearthed regularly by researchers and can be seen in Pit 91 observation stations. In addition to Pit 91 there is another ongoing digging called "Project 23". Paleontologists supervise and direct volunteer work on both sites.
Excavation of "Project 23" and the newly discovered hole Edit
On February 18, 2009, the George C. Page Museum officially announced the discovery of 16 fossil deposits in 2006 that had been removed from the ground during the construction of the underground parking garage for the Los Angeles County Museum of Art next to the tar pits. Among these findings are the remnants of the sharp-toothed cat, the awful wolf, the bull, the horse, the giant land, the tortoise, the snails, the shells, the thousand feet, the fish, the goffer, and the American lion. Also found is the almost intact mamut frame, dubbed Zed; the only missing pieces were the hind legs, vertebrae and the top of the skull, which were shaved by construction equipment in preparation for building the parking structure.
These fossils are packed in boxes at construction sites and moved to the complex behind Pit 91, in the Page Museum property so construction can continue. Twenty-three large accumulations of tar and specimens were brought to Page Museum. This deposit is done under the name "Project 23". Since the work for Metro Purple Line public transport is extended, museum researchers know more tarred pits will be found, for example near the junction of Wilshire and Curson. In an exploration subway excavation in 2014 at Miracle Mile, prehistoric objects are found including geoducks, sand dollars, and a 10 foot branch of pine trees, of a kind now found in the central jungle of California.
Flora and fauna Edit
Among the prehistoric species associated with La Brea Tar Pits are mammoth Pleistocene, horrible wolves, short-faced bears, land slots, and California state fossils, sharp-pointed cats ( Smilodon fatalis ).
Only one human has been found, the partial skeleton of La Brea Women dates to about 10,000 calendar years (c. 9,000 radiocarbon years) BP, who was 17 to 25 years of age at death and found to be associated with domestic dog remains, and so interpreted to have been buried ceremonially. John C. Merriam of the University of California led many early work in identifying species early in the 20th century.
This park is known for producing many fossil mammals that originate from the last glacial period. While fossil mammals generate significant interest, other fossils, including fossil insects and plants, and even pollen, are also appreciated. These fossils help determine the picture of what is supposed to be a colder and damper climate in the valley of Los Angeles during the glacial period. Among these fossils are microfossils, taken from the asphalt matrix and sandy clay by washing with solvents to remove the oil, then picking up the remains under a high-powered lens.
Tar holes around the world are unusual in collecting more predators than prey. The reason for this is unknown, but one theory is that large prey animals will die or get trapped in a tar pit, pulling predators from a distance. This predator trap will catch predators along with their prey. Another theory is a terrible wolf and their prey may be trapped during the hunt. Since modern wolves hunt in packs, any predator animals can pick up some wolves with it. The same may also be true of the known sword-toothed ( Smilodon fatalis ) of the area.
Popular culture Edit
Movies filmed in La Brea Tar Pits include Fire Mountain , My Girl 2 , Miracle Mile , "The Last Action Hero", and Seven Psychopaths .
See also Edit
References Edit
External links Edit
- Museum Page - La Brea Tar Pits
- The UCMP Berkeley website: explains the geology and paleontology of asphalt seepage.
- Gocalifornia.com: La Brea Tar Pits - visitor guide .
- Palaeo.uk: "Setting the La Brea site in context."
- NHM.org: Excavation Hole 91
Source of the article : Wikipedia
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