La Brea Pitch Lake
The La Brea Pitch Lake [ ˈpʰɪt͡ʃ leik ] (English for La Brea Pechsee ) is a natural, superficial accumulation of asphalt ( asphalt lake ) and the world's largest occurrence of this type. The lake is located in the southwest of the Caribbean island of Trinidad near the city of La Brea (which also means “bad luck” in Spanish ). For Trinidad, the lake is a major tourist attraction and an important economic factor at the same time.
General
La Brea Pitch Lake covers an area of approximately 40 acres . Its depth is given differently with 75 to 100 meters. More precise test results are not available. The total amount of asphalt is estimated at 10 million tons.
Asphalt "see" is a rather misleading term, because the asphalt is almost nowhere liquid on the surface. Instead, the surface of the lake is slightly wavy, wrinkled and hardened to such an extent that it is mostly accessible. There is water in depression. The fact that the asphalt underneath is not really firm is expressed in the fact that the "lake surface" is springy in some places or the soles of the shoes pull sticky threads when walking over them. At times when the asphalt was removed with pickaxes , even sixty centimeter deep holes closed by themselves within two days. The area around the lake is also on asphalt and is therefore relatively unstable. The consequences are houses that are out of balance, arched floors and cracked house walls. The center of activity is in the middle of the lake, the so-called Mother of the Lake , where gases and fresh asphalt rise, causing the remaining asphalt masses to be circulated in all directions towards the edge: as if one had failed Deep drilling the rod broke, it later reappeared in another place, grotesquely deformed. Another indication of the movements of the asphalt are isolated vegetation islands that constantly change their position.
The asphalt lake has been on the Trinidadian tentative list , the list of proposals for the UNESCO World Heritage Convention, since 2011 . Similar formations, albeit to a lesser extent, are found in the asphalt ponds of La Brea Tar Pits in Los Angeles .
geology
At the bottom of the lake, viscous asphalt (“earth pitch”) penetrates from the depths and mixes with rock fragments. This mixture is called " Trinidad natural asphalt ". It is believed that the asphalt penetration is related to the location of the island of Trinidad in the border zone between the Caribbean plate and the South American plate . The oblique convergence of the two plates exerts pressure on an oil deposit lying underground on the island . The high pressure leads to the formation of hot bitumen, which seeks its way up and finds an exit on the island. This tectonic constellation arose in the course of the later Tertiary .
microbiology
In 2014, an article was published in the journal Science , according to which microorganisms in tiny water droplets (1 to 3 μl ) decompose the petroleum from the inside out even in the greatest depths of La Brea Pitch Lake . According to Rainer Meckenstock from the University of Duisburg-Essen , this could be an indication that large parts of the world's oil reserves have already been broken down by microorganisms into methane and carbon dioxide .
Economical meaning
Due to its robust quality, Trinidad natural asphalt was a sought-after additive in road construction worldwide . 150 to 200 tons of asphalt were mined daily and used for export. In Germany alone, 6,000 tonnes of public roads were used every year. The holes created during mining close again in a very short time due to the asphalt flowing in from the depths. In 2005, asphalt mining came to a standstill.
Every year around 20,000 tourists visit the "ugliest attraction in the Caribbean" and thus constitute an additional economic factor for Trinidad. There are regular and individually bookable touristic tours. Most of the lake has hardened on the surface and is accessible to humans.
Myth and History
According to an Indian legend, a rich village with large orchards used to stand on the site of La Brea Pitch Lake. As more and more birds feasted on the fruit, the villagers hunted and ate them, including the sacred hummingbirds . For this outrage the gods punished the people and let the village sink into the earth overnight. In its place the asphalt lake was built, which from then on was considered the entrance to the underworld.
According to another version of this legend, which is expressively told in a wall painting on the viewing terrace above the lake, one of the holy hummingbirds is said to have been killed by their chief during a victory celebration of the warlike Indian tribe of the Chaima.
The lake was already known to the Spanish colonial rulers of the 16th century, who called the region "Tierra de Brea". Walter Raleigh repaired ships in his expedition fleets here in 1595 and 1617. La Brea was founded between 1617 and 1797. At that time, the tar lake was not used economically, rather sugar and coffee were grown. A first refinery for the tar was built in 1792 at the behest of the governor José María Chacón . The commercial exploitation of the tar lake began in 1850 by Thomas Cochrane , who researched the possible uses of tar, which initially resulted in a patent for the propulsion of steam ships by burning bitumen . After Conrad Stollmeyer, of German descent, joined the company, the focus was on selling tar for road construction. From around 1960 the asphalt business slackened noticeably; Since the 2000s, asphalt has only been mined to a small extent.
literature
- Ed. Graefe: The asphalt lake on the island of Trinidad and recycling of the Trinidad asphalt. In: Journal of Applied Chemistry. Vol. 26, 1913, ISSN 0932-2132 , pp. 233-239.
Web links
- Pictures from the Asphaltsee (German)
Individual evidence
- ↑ LiverpoolMuseums.org.uk: "The" Pitch Lake. Retrieved March 19, 2018 .
- ↑ UNESCO.org: Trinidad and Tobago. Retrieved May 8, 2017 .
- ↑ James L. Pindell, Stephen F. Barrett: Geological Evolution of the Caribbean Region: A plate-tectonic perspective. In: G. Dengo, JE Case (Ed.): The Geology of North America. Volume II: The Caribbean Region. Geological Society of America, Boulder (CO) 1990, pp. 405-432
- ↑ How does life in oil work? . idw science information service. Retrieved September 2, 2014
- ↑ Tilasto.com: Trinidad and Tobago: Bitumen asphalt, exports (thousand metric tons). Retrieved August 25, 2020 .
- ↑ Michael Anthony: Towns and Villages of Trinidad and Tobago . 2nd Edition. Printmaster, Marabella 2001, ISBN 978-0-00-976806-4 , p. 123 .
Coordinates: 10 ° 14 ′ 3.5 ″ N , 61 ° 37 ′ 38.2 ″ W.