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Unit 7 Chapter 23 The Ocean Basin
Section 1 The Water Planet
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Divisions of the Global Oceans
5 Major Oceans
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Seas
A sea is a smaller body of water that may be partially
surrounded by land.
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Exploration of the Ocean
Oceanography
Oceanography _____________________________________
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In approximately the 1850’s the ocean started to become a popular
laboratory.
The Birth of Oceanography
In 1855 Matthew F. Murray published the first known textbook on the
oceans with information that he collected from Navy records about
the currents, winds, depths and weather conditions.
In 1872 the scientists aboard the H.M.S. Challenger made some
discoveries that we still use today. In WWII scientists developed
sonar recordings and magnetic recordings of the ocean floors.
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Sonar - Sound Navigation and Ranging
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Sound signals are sent through the water to the sea floor. By
tracking how long it takes for them to bounce back, the depth can be
determined.
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Bouncing back signals from space can map the area. The
waves can not penetrate to the sea floor, but they still can create a
high resolution sea floor map based on the height of the sea level.
Submersibles
These are under water research vessels which are piloted by people.
Sometimes they will use robotic submersibles to reach areas too
dangerous for humans.
Underwater Research
Scientists have found unusual life communities underwater.
Section 2 Features of the Ocean Floor
The ocean floor has 2 major areas; ________________________
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The Continental Margin
The continental margin is the shallow sea-floor that is located
between the shoreline and the deep ocean bottom.
Continental Shelf
The continental shelf extends from the shore line out toward the
continental slope.
The Continental Slope and the Continental Rise
Continental Slope
The continental slope begins at the shelf edge where depth
increases rapidly.
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Continental Rise
The continental rise is several kilometers thick, descends
gradually from the continental slope to the ocean floor.
Submarine Canyons
Very deep canyons probably formed during the end of the Ice
Ages when glaciers melted and covered the valleys
Turbidity Currents
Triggered by earthquakes. They are landslides that go down
the continental slope.
Deep Ocean Basins
Deep ocean basins have distinct features. Some include the highest
mountains, and the flattest plains.
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Trenches are long, narrow depressions located in the deep ocean
basins. The Mariana Trench is the Western Pacific is the deepest
place on Earth’s Crust
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The abyssal plains are considered some of the flattest lands
surfaces on Earth; (Argentina’s coastal abyssal plain rises 3 meters
over 1300 km). More of the located in the Atlantic Ocean than
anywhere else.
Abyssal HillSmall rolling hills underwater. In the Atlantic Ocean they run
parallel in either side of the mid-ocean ridge.
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Remember the volcano chapter.
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Seamounts are submerged volcanic mountains; the beginning of an
Island.
Section 3 Ocean-Floor Sediment
Sediments depend on where they are from and usually are well
sorted.
Sources of Deep Ocean Basin Sediments
Samples are usually taken by core sampling. A core sample requires
a long tube shoved into the ocean floor and sediments scooped out
as a cylindrical piece.
Inorganic Sediments
Sediments produced by non-living things
Biogenic Sediments
Sediments produced by living things
Chemical Deposits
Crystallized dissolved material
Physical Classification of Sediments
There are 2 classifications
Mud and Ooze