Warm Up 12-5-14
• 1. What are the four minerals that
compose salt water?
• 2. What are the three reasons the ocean
is salty?
• 3. What percentage of a drop of water
contains sea salt?
• 4. What are the parts of the continental
margin?
Ocean Landforms
The Ocean Floor
Revealing the Ocean Floor
• If you could travel to the
bottom of the ocean, you
would see the world’s largest
mountain chain and canyons
much deeper than the Grand
Canyon.
• How can the ocean floor be
mapped?
Revealing the Ocean Floor
 Sonar (stands for Sound
Navigation and Ranging)
 Invented in the 1920s
 Primary instrument for
measuring depth
 Reflects sound from ocean
floor
Revealing the Ocean Floor
 Use of satellites for mapping
 Employs satellites equipped with radar
altimeters
 Scientists are able to measure the
direction and speed of ocean currents.
 Measure the different heights of the
ocean water surface to make maps of
ocean floor.
 Can cover more territory using
satellites rather than ship sonar.
Continents Edge
• Called the continental margin
• Three parts
–Continental shelf
–Continental slope
–Continental rise
Continental Shelf
• Begins at the shoreline,
Depth can reach 200
meters, meets the
continental slope.
• This is what you walk on at
the beach.
Continental Slope
•Begins at the edge of
shelf, Depth ranges from
200 meters to 4000
meters
•Continent ends at bottom
of continental slope
Continental Rise
• Slopes more gently
• Made of sediments that come
off the shelf
• Like underwater
avalanches of
sediment and
water
Abyssal Plain
• Broad, flat portion of the
deep-ocean floor.
• Covered with mud and
remains of marine
organisms.
• Average depth is 4,000
meters
Mid-Ocean Ridges
• Mountain chains formed where
tectonic plates pull apart.
• Pulling motion creates cracks in
the crust called rift zones.
• Rift Valley forms between
mountains in the mid-ocean
ridge.
Seamounts
• Individual mountains of
volcanic material.
• If a seamount builds up
above sea level, it becomes
an island.
• A guyot is a flat-topped
seamount.
Actual footage of an erupting
underwater volcano.
Ocean Trench
• bottomless cracks in the
ocean basin (floor).
• Formed where one oceanic
plate is forced underneath
another plate.
• Most famous:
Marianas Trench