East Pacific Rise

East Pacific Rise
a long north-south elevation of the sea floor in the E Pacific Ocean extending southward from SW Mexico to the Antarctic Ocean.

* * *

Submarine linear mountain range on the floor of the South Pacific Ocean, roughly paralleling the western coast of South America.

The main portion of the rise lies generally about 2,000 mi (3,200 km) off the coast, and it lies about 6,000–9,000 ft (1,800–2,700 m) above the surrounding seafloor. The East Pacific Rise has a generally smooth and flattish surface, and it drops sharply away at the sides. It is composed largely of basic igneous crust, overlain or abutted by more or less flat-lying sediments.

* * *

      linear submarine volcanic chain on the floor of the southeastern Pacific Ocean, roughly paralleling the west coast of South America. The East Pacific Rise forms part of the circumglobal system of active volcanic ridges, all of which define the position of diverging plates where new crust is being created. Such ridges represent the locus of global shallow-water earthquakes.

      The main portion of the rise lies generally about 2,000 miles (3,200 km) off the coast. Its northernmost outliers extend as far north as the mouth of the Gulf of California, where it joins the transform zone of the Pacific–North American Plate boundary. From its southernmost point, near 55° S latitude and 130° W longitude, it continues in a west-southwesterly direction as the Pacific-Antarctic Ridge to approach Antarctica south of New Zealand. The surface of the East Pacific Rise is basically smooth and flattish, and it drops sharply away at the sides. Its structure is largely of igneous crust, overlain or abutted by generally flat-lying sediments. It rises from approximately 6,000 to 9,000 feet (1,800 to 2,700 metres) above the surrounding seafloor and is extensively fractured by faults mostly occurring at intervals of roughly 200 miles (320 km).

      The East Pacific Rise and its associated features to the north and southwest form the eastern and southern boundaries of the Pacific Plate, where it abuts (from north to south) the North American, Cocos, Nazca, and Antarctic plates. The crest of the East Pacific Rise is a centre of seafloor spreading; new oceanic crust in the form of basaltic lava is welling up along the crest, cooling, and moving away from the crest in either direction. Offshore from Chile and Peru the rate of spreading is about 6.3 inches (16 cm) per year, one of the most rapid rates on Earth, though it decreases to about 2.4 inches (6 cm) at the mouth of the Gulf of California. Associated with this volcanic activity are a number of hydrothermal vents, upwellings of heated seawater that often carry a variety of sulfide minerals. These vents support organisms that exist through chemosynthesis by sulfur-fixing bacteria.

* * *


Universalium. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • East Pacific Rise — The East Pacific Rise is a mid oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from (north to south) the North American Plate, the Rivera Plate, the Cocos …   Wikipedia

  • East Pacific Rise — a long north south elevation of the sea floor in the E Pacific Ocean extending southward from SW Mexico to the Antarctic Ocean …   Useful english dictionary

  • Pacific Ocean — an ocean bordered by the American continents, Asia, and Australia: largest ocean in the world; divided by the equator into the North Pacific and the South Pacific. 70,000,000 sq. mi. (181,300,000 sq. km); greatest known depth, 35,433 ft. (10,800… …   Universalium

  • Pacific Ring of Fire — The Ring of Fire redirects here. For other uses of the term, see Ring of Fire (disambiguation). The Pacific Ring of Fire (see below) …   Wikipedia

  • Pacific Ocean — <p></p> <p></p> Introduction ::Pacific Ocean <p></p> Background: <p></p> The Pacific Ocean is the largest of the world s five oceans (followed by the Atlantic Ocean, Indian Ocean, Southern Ocean,… …   The World Factbook

  • Pacific Plate — The Pacific Plate is an oceanic tectonic plate beneath the Pacific Ocean.To the north the easterly side is a divergent boundary with the Explorer Plate, the Juan de Fuca Plate and the Gorda Plate forming respectively the Explorer Ridge, the Juan… …   Wikipedia

  • pacific — /peuh sif ik/, adj. 1. tending to make or preserve peace; conciliatory: pacific overtures. 2. not warlike; peaceable; mild: a pacific disposition. 3. at peace; peaceful: a pacific era in history. 4. calm; tranquil: The Wabash is a pacific river.… …   Universalium

  • east — eastness, n. /eest/, n. 1. a cardinal point of the compass, 90° to the right of north. Abbr: E 2. the direction in which this point lies. 3. (usually cap.) a quarter or territory situated in this direction. 4. the East, a. the parts of Asia… …   Universalium

  • Pacific-Antarctic Ridge — The Pacific Antarctic Ridge (PAR) is a divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate. It is regarded as the southern section of the East Pacific Rise in …   Wikipedia

  • Pacific Plate — Geol. one of the major tectonic divisions of the earth s crust, comprising four sea floor basins; separated from the Nazca, Cocos, and North and South American plates by the East Pacific Rise and San Andreas fault and bounded in the western… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”