The Ocean Floor

The ocean basins have the same geological features as the continents; however, these features are far more exaggerated. The ocean floor contains broad plains that are flatter than those on land, volcanic mountains which are taller and volcanic mountain ranges which are far more extensive than their continental cousins.

The ocean floor has an extremely diverse terrain. The ocean floor actually contains the tallest mountains, the deepest valleys and the flattest plains that exist on the Earth!

The continental slope is a gradually sloping end of a continental shelf that extends out under the ocean. There is a significant difference between the continental shelf on either side of the North American plate.

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The continental slope is the end of the continent extending from the outer edge of the continental shelf down to the ocean floor.

Abyssal plains are flat sea floor areas created by sediments that settle on the ocean floor. Some abyssal plains have small hills and underwater inactive volcanic peaks. These volcanic peaks are called seamounts. Sometimes the peaks of these seamounts are worn down to create plateau-like tops. These flat-topped seamounts are called guyots. Several seamounts and volcanic islands can form curving chains near oceanic trenches. These chains of peaks are referred to as island arcs. Examine the drawing below and see if you can find all of these features.

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Mid- ocean ridges are found in all of the ocean basins. These ridges are areas where new ocean floor is formed.

The Earth’s uppermost plates move and separate and allow hot magma to form new crust. This process is called sea floor spreading.

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At other locations on the ocean floor, old ocean floor slides beneath another plate and goes back into the earth’s mantle. This area is called a subduction zone.

Subduction zones are marked by deep ocean trenches, which are long, narrow steep depressions where one plate sinks beneath another. The Mariana trench is the deepest point in the on the Earth is located at a subduction zone. This trench is so deep that Mount Everest could easily fit inside it.