Transcript Ocean Floor Power Point

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 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
• Continues until it begins to
slope more steeply
downward
• Depth can reach 200
meters
• This is what you walk on at
the beach.
Continental Slope
•Begins at the edge of
shelf and continues to
flattest part of ocean
floor
•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
• Seemingly bottomless
cracks in the ocean basin.
• Formed where one oceanic
plate is forced underneath
another plate.
• Most famous:
Marianas Trench