Essential Question:

How are the geological features that exist on land similar to the geological features on the ocean

floor?

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• The world ocean can be divided into four main ocean basins—the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean.

• The Pacific Ocean is the largest and has the greatest depth

• The Atlantic Ocean is about half the size of the Pacific and not quite as deep.

• The Indian Ocean, largely a southern hemisphere body, is slightly smaller than the Atlantic.

• The Arctic Ocean is about 7 percent of the size of the Pacific.

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• The topography of the ocean floor is as diverse as that of the continents

• Today’s technology—particularly sonar, satellites, and submersibles—allows scientists to study the ocean floor in a more efficient and precise manner than ever before.

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• Sonar is an acronym for sound navigation and ranging. It is also referred to as echo sounding.

• Sonar works by transmitting sound waves toward the ocean bottom.

• The sonar equipment on a ship sends out pulses of sound that bounces off the ocean floor

• The equipment then measures how quickly the sound wave returns to the ships

Satellites

• Satellites are able to measure small differences by bouncing microwaves off the ocean surface.

• Using this new technology, scientists have discovered that the ocean surface is not perfectly flat.

Submersibles

• Submersibles are small underwater crafts used for deep-sea research

• Today, many submersibles are unmanned and operated remotely by computers. These remotely operated vehicles (ROVs) can remain underwater for long periods.

Let’s go exploring…

• Lets journey to the bottom of the ocean floor!

• As we leave the harbor, we make our way over a section of the ocean floor called the continental shelf…

Shallow Water

• A continental shelf is the gently sloping submerged surface extending from the shoreline.

• Continental shelves contain important mineral deposits, large reservoirs of oil and natural gas, and huge sand and gravel deposits.

• A continental slope is the steep gradient that leads to the deep-ocean floor and marks the seaward edge of the continental shelf.

• A continental rise is the gently sloping surface at the base of the continental slope.

Open Ocean

• Deep ocean basin, which is about 2.5 to 3.5 miles deep, covers 30 % of Earth's surface and has features, such as abyssal plains, deep-sea trenches and seamounts.

• Abyssal Plains is the broad, flat area of the ocean floor with thick layers of mud and silt. It also contains thick layers of sediment, formed by the sunken remains of dead organisms form the surface.

• Mid-Ocean Ridges are the mountain chains formed where tectonic plates pull parts

• Rift Valley is the area between two tectonic plates that have moved apart

Open Ocean

• Seamounts are mountains found below the ocean whose peaks have not reached the surface

• Ocean Trench is seemingly bottomless cracks in the ocean floor found at subduction zones

• Volcanic Island is a mountain on the ocean floor whose peak has reached above the water’s surface