Seafloor Geology
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"" Ring of Fire ""

What is the world's largest ocean?


Hydrothermal Vents:
Exploring G
eysers on the Seafloor

Crust: Thickness 3-120 km

Mantle: Thickness 2,900 km

Liquid Outer Core: Thickness 2,225 km

Solid Inner Core: Thickness 2,400 km

The deeper you go into Earth's interior, the hotter it gets, The inner core is believed to be as hot as 5,500°C (10,000°F)!

Many of us are familiar with “Old Faithful,” a geyser in Yellowstone National Park in the United States. This geyser erupts several times a day, spouting boiling water heated by volcanic rock deep within the Earth’s crust.

A hydrothermal vent is a geyser on the seafloor. It continuously gushes super-heated, mineral-rich water that supports a diverse community of organisms.

Although most of the deep ocean is sparsely populated, vent sites teem with a fascinating array of life, from towering tubeworms to little-known species of octopus.

Hydrothermal vents were discovered in 1977 in the Pacific Ocean. Since then, they have been found in the Atlantic, Indian, and Arctic oceans. Most vents occur at an average depth of about 2,100 meters (7,000 ft) in areas of seafloor spreading along the Mid-Ocean Ridge system — the underwater mountain chain that snakes around the globe.

How do hydrothermal vents form? In some areas along the Mid-Ocean Ridge, the huge plates that form the Earth’s crust are moving apart, causing deep cracks in the ocean floor. Seawater seeps into these openings and is heated by the molten rock, or magma, beneath the crust. As the water heats up, it rises.

When this “hot spring” gushes out into the ocean, its temperature may be as high as 400°C (752°F) or more. Yet this water typically does not boil because of the pressure from the tremendous weight of the ocean above.

Chimneys top some vents. These smokestacks are formed from dissolved metals that precipitate out (form into particles) when the super-heated vent water meets the surrounding seawater, which is only a few degrees above freezing.

Geologists are intrigued by how rapidly vent chimneys grow — as much as a whopping 30 centimeters (12 in) a day! “Godzilla,” a vent chimney in the Pacific Ocean off Oregon, reached the height of a 15-story building before it toppled. In 2000, University of Washington scientists discovered the “Lost City” vent field in the Atlantic Ocean. It has the tallest vent chimneys known, up to 60 meters high (196 ft).

There are many reasons why scientists want to learn more about hydrothermal vents. Besides providing habitat for an intriguing community of life, these underwater geysers are believed to play an important role in the ocean’s temperature, chemistry, and circulation patterns.

Scientists also are fascinated by the unusual life that inhabits vent sites. These creatures who live in darkness, from tiny bacteria to giant tubeworms, may light the way to the development of new drugs, industrial processes, and other products useful to us all.

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How deep is the ocean

mariana trench

The Mariana Trench is a depression in the Pacific Ocean, east of the Mariana Islands. It is 1,554 miles long and averages 44 miles wide. Within it, about 210 miles southwest of Guam, lies the deepest known point on Earth. Named the "Challenger Deep" for the British survey ship Challenger II that located it in 1951, this underwater gorge plunges to a depth of nearly 7 miles!

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Earth Science? Eggzactly

To understand Earth's structure, think of a hard-boiled egg. The crust is like the egg's thin shell. The mantle is the egg white, and the core is the yolk. However, the Earth's core is divided into two parts: a liquid outer core and a solid inner core.




An educational program sponsored by:

National Science Foundation
University of Delaware
The University of Waikato
University of Southern California
University of Colorado
University of North Carolina
Universidad Nacional Autónoma de Mexico
J. Craig Venter Institute
Mo Bio Laboratories Inc.


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