Transcript Unit 7 Chapter 23

Unit 7 Chapter 23
The Ocean Basin
Section 1 The Water Planet
The global ocean contains more than 97% of all the water on or near the
Earth’s surface.
Divisions of the Global Oceans
5 Major Oceans
They are the:
Atlantic, Pacific, Indian, Artic and the Southern Oceans.
Seas
A sea is a smaller body of water that may be partially surrounded by
land.
Mediterranean Sea
Caribbean Sea
South China Sea
Exploration of the Ocean
Oceanography
Oceanography is the scientific study of the ocean using chemistry,
biology, physics, geology and other sciences.
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.
Sonar - Sound Navigation and Ranging
Echo Sounding (sonar)-
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.
Satellite Observing-
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 used 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; the continental margin
and the deep ocean basin.
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.
Continental Rise
• The continental rise is several kilometers thick, descends gradually
from the continental slope to the ocean floor.
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.
Trenches
• 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
Abyssal Plains
•
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 Hill-
•
Small rolling hills underwater. In the Atlantic Ocean they run parallel
in either side of the mid-ocean ridge.
Mid-Ocean Ridges
• Remember the volcano chapter.
Seamounts
• 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