Journey to Bottom of the OceanOcean Floor

Mehtab AhmedLecturerDepartment of GeographyGC University Faisalabad

Continent

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•Asia

•Africa •North America •South America •Antarctica •Europe •Australia

•A continent is a large landmass. •There are seven continents on the Earth

We will begin our journey where land meets the ocean.

Do you know where we are?

Yes. At the beach.

Beaches are the fastest changing part of the ocean. They change with every wave.

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Zones of the Ocean

There are several basic “zones”:•Continental margins (continental shelves, continental slopes, and continental rises)•Abyssal plains (which may contain abyssal hills, sea mounts, and guyots)•Mid-Oceanic ridge system (largest mountain range in the world, with central rift valley)•Deep-sea trenches, island arcs, and other marginal features

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Click on a feature to go there or click next to continue with the journey

Rift

Continental Shelf

There are several part to the continental shelf.

– The continental break

– The continental slope

– The continental rise

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The edge of the continents slope down from the shore into the ocean. The part of the continent located under water is known as the Continental Shelf.

The continental shelf is rich in resources such as marine life, minerals and oil. For this reason, countries around the world claim the bordering continental shelf as part of their territories.

Continental Slope

The continental slope is a steep slope that connects the continental- shelf to the bottom of the ocean floor. The slope begins at a depth of around 460 feet (140 meters).

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Volcanic Island Arc

• Volcanic island arcs are a series of seamount tall enough to break the sea surface and form an island.

• The Augustine Island Volcano in Alaska is an example of a volcanic arc.

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Abyss• The deepest point in the ocean is

called the abyss

• The Mariana Trench is the deepest known point in the ocean. It is located in the western part of the Pacific Ocean near the fourteen Mariana Islands.

• The Mariana Trench is a semi-circle that extends from the northeast to the southwest for about two thousand five hundred fifty meters and is seventy kilometers wide. Back to Map

Mid Ocean Ridge

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•The mid ocean ridge is a series of mountain ranges on the ocean floor.

•They are more than 84,000 kilometers (52,000 miles) in length and they extend through the North and South of the Atlantic ocean, the Indian Ocean, and the South Pacific ocean.

•According to the plate tectonics theory, volcanic rock is added to the sea floor as the mid-ocean ridge spreads apart.

Abyssal Plain

Abyssal plains are the vast, flat, sediment-covered areas of the deep ocean floor. They are the flattest, most featureless areas on Earth. These flat abyssal plains occur at depths of over 6,500 ft (1,980 m) below sea level.

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Seamount

• Seamounts are undersea volcanic mountains rising from the bottom of the sea that do not break the water's surface

• Seamounts are usually isolated and cone-shaped, often volcanic in origin.

• Smaller volcanoes are called sea knolls, and flat-topped seamounts are called guyots.

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Guyot• Guyots are seamounts that have built

above sea level. Over time erosion by waves destroyed the top of the seamount resulting in a flattened shape

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Seamount rises above water

Erosion by waves flattens the top of the mount

The seamount becomes submerged to form a Guyot

Ocean Trench

• A deep-sea trench is a narrow, elongate, v-shaped depression in the ocean floor.

• Trenches are the deepest parts of the ocean, and the lowest points on Earth.

• They reach depths of nearly 7 mi (10 km) below sea level.

• They can be thousands of miles in length, yet as little as 5 mi (8 km) in width. Back to Map

Rift

• A rift valley is formed where two tectonic plates pull apart from one another creating a deep valley.

• Rifts are the opposite of mountain ranges like the Alps or the Himalayas where the plates push together to create a mountain

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Compare continental and oceanic landforms

Continental landform

Canyon

Valley

Volcanic mountain

Mountain Range

Low hills or plains

Oceanic landform

TrenchRiftSeamount

Mid-ocean ridge

Ocean basin (abyssal plains)

Sources• http://www.utdallas.edu/~pujana/oceans/guyot.html

• http://www.enotes.com/earth-science/abyssal-plains

• http://www.answers.com

• http://images.google.com/images?um=1&hl=en&rlz=1T4ADBF_enUS279US280&q=ocean+trench+pictures

• http://oceanexplorer.noaa.gov/explorations/02galapagos/logs/jun04/jun04.html

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