Download CH20: The Ocean Floor - Van Buren Public Schools

Spring Hydrology 2016
Mrs. Kummer
The Water Planet
 Nearly ¾ of Earth’s surface is underwater
 97% of all water on Earth is in the “global ocean”
 The global ocean is only massive as a surface
area….as a volume and mass it is tiny
 Volume of solid earth = 800X greater than that of
water in the global ocean
 Mass of global ocean is only 1/4,000 of Earth
What Parts Make Up the Global Ocean?
 How many Oceans are there?
 5 total: Pacific, Atlantic, Indian, Arctic, and
Southern-NOAA does NOT consider this an ocean
 How many seas are there?
 Many! Examples?
 All Oceans and Seas are saltwater (CH21)
 NOAA = National Oceanic and Atmospheric
Administration
What are some features of these oceans?
 Pacific Ocean is the largest feature on Earth
 Contains > ½ of the ocean water on Earth
 Average depth = 3.9km (almost 3 miles) makes it the
deepest
 Contains: Sea of Japan, Bering Sea, South China Sea
 Atlantic Ocean is the next largest
 Average depth = 3.6km
 Contains: Mediterranean, Caribbean, and Baltic Seas
 Indian Ocean is the next largest
 Average depth = 3.8km
 Contains Arabian and Red Seas
 Southern Ocean is the next largest
 Arctic Ocean is the smallest
What is Oceanography?
 Study of physical characteristics, chemical
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composition, and life forms of the ocean
Benjamin Franklin first mapped the gulf stream in
1769-1770 (even though sailors used it for 200 years
before he named it…)
The birth of Oceanography was 1842-1861 when the
superintendent of the US Naval Observatory,
Matthew Maury, spent his career on Oceanography
He released his book in 1855 and distributed it
globally
It is considered one of the “newer sciences” like
Physics/Calculus/Nuclear Energy
How Do You Explore the Ocean Floor?
 Submersibles
 Bathosphere (Spherical diving vessel tethered to
ship above carrying scientists)
 Bathyscaph (Self-Propelled, free-moving sub)
 Sonar (Sound Navigation and Ranging)
 Let’s review some of the names of equipment from
the movie
 Movie Facts
Continental Margin
 That portion of the seafloor adjacent to the
continents; it may include the continental
shelf, continental slope, and continental
rise.
Continental Shelf
 The gently sloping surface at the base
of the continental slope.
Continental Slope
 The steep gradient that leads to the deep-
ocean floor and marks the seaward edge of
the continental shelf.
Submarine Canyon
 A seaward extension of a valley that was cut
on the continental shelf during a time when
sea level was lower; a canyon carved into the
outer continental shelf, slope, and rise by
turbidity currents.
Turbidity Current
 A downslope
movement of dense,
sediment-laden water
created when sand
and mud on the
continental shelf and
slope are dislodged
and thrown into
suspension.
Continental Rise
 The gently sloping surface at the base of the
continental slope.
Ocean Basin Floor
 Area of the deep-ocean floor between the
continental margin and the oceanic ridge.
Abyssal Plains
 Very level area of the deep-ocean floor,
usually lying at the foot of the continental
rise.
Seamounts
 An isolated volcanic peak that rises at least
1000 meters above the deep-ocean floor.
Mid-Ocean Ridge
 A continuous elevated zone on the floor of
all the major ocean basins and varying in
width from 1000 to 4000 kilometers.
Seafloor Spreading
 The process by which plate tectonics
produces new oceanic lithosphere at ocean
ridges.
Key Concept
Atlantic Ocean makes ocean floor
daily at Mid Ocean Ridge (MOR)
Pacific Ocean destroys ocean floor
daily at Subduction zones.
Key Concept
What are the three main regions of
the ocean floor?
 The floor regions are: continental
margins, ocean basin floor, and midocean ridge.
Key Concept
How do continental margins in the
Atlantic Ocean differ from those in the
Pacific Ocean?
 The Atlantic Ocean has thick layers of
undisturbed sediment cover with very
little volcanic or earthquake activity.
 The Pacific Ocean crust is plunging
beneath continental crust and experiences
both volcanic and earthquake activity.
Key Concept
How are deep-ocean trenches
formed?
 Trenches are formed at sites of plate
convergence where one moving plate
descends beneath another and
plunges back into the mantle.
Key Concept
How are abyssal plains formed?
 The sediments that make up abyssal
plains are carried there by turbidity
currents or deposited as a result of
suspended sediments settling.
Key Concept
What is formed at mid-ocean
ridges?
 New ocean floor is formed at mid-
ocean ridges as magma rises between
the diverging plates and cools.