Transcript Ocean Floor Powerpoint

Draw and Label the Parts of a Wave
A.
B.
C.
D.
How is the ocean
floor studied??
Sonar
 SOund NAvigation and Ranging
 Sonar signal sent to ocean floor
 Time how long it takes to reach bottom and return to
surface
 Side Scan Sonar
 Technique that directs sonar waves at an angle
Calculating Depth
 D = (1500 m/s) (time / 2)
 1500 m/s = speed of sound in water
 Example:
 If sound signal takes 4 seconds how far away is the
ocean floor at that location?
 D = (1500 m/s) (4s/2)
 D = (1500 m/s) (2s)
 D = 3000 m
Submersibles
 Deep Diving Submersible
 2-3 person vessel
 Can reach moderate to deep depths
 Excellent horizontal movement
Self Contained Diving
 1940s - Developed first
practical scuba (aqua
lung)
 Released compressed air
when diver inhaled
 Divers could swim freely
rather than walk along
bottom
SCUBA= Self Contained Underwater Breathing Apparatus
Ocean Floor
 Continental Margin
 Area where the edges
of the continents meet
the ocean
 Shallowest part of
ocean
 Includes:
 Continental Shelf
 Continental Slope
 Continental Rise
Continental Shelf
 Shallowest part of
continental margin
 Extends into ocean from
shore
 Average width is 60 km
 Depth of water – 130 m
Continental Slope
 Quick drop in the seafloor
 True edge of continent
 Turbidity Currents
 Fast moving water currents along sea floor that carve out
submarine canyons
Continental Rise
 Gently sloping
accumulation of
sediment at the bottom
of the continental slope
Ocean Floor Features
 Abyssal Plains
 Flattest part of the ocean floor
 5 to 6 km below surface
 Seamounts
 Underwater basaltic volcanoes
 Guyots
 Large, extinct, volcanoes with flat submerged
tops
Ocean Basins
 Mid-ocean Ridge
 Underwater chain of
mountains
 Mid-Atlantic Ridge
 Deep Sea Trenches
 Deep Elongated
Depressions
 Marianas Trench
Hydrothermal Vents
 At rift zones, water seeps
through cracks and gets
heated.
 Hot water rises
dissolving minerals out
of rocks as it flows
Hydrothermal Vents
 Water emerges from
seafloor and comes in
contact with cold water
 Minerals in hot water
form a dark cloud called
a Black Smoker
Hydrothermal Vents
 Submersibles
visited vents more
than 2400 meters
deep
 Temperatures can
get as high as 371
Celsius
Case Study
 1977 – Alvin
 Parts of seafloor near
vents had thick
growth of living
things
 Water very rich in
minerals
 H2S – Hydrogen
Sulfide
Alvin
 High Concentration of
bacteria
 Bacteria uses H2S to
make food
 Share food with other
creatures
 Chemosynthesis
Vent Crab
Pompeii Worm
Tubeworms
Vent Life
Giant Clam
Life Span of Hydrothermal Vents
 Life span varies (months to decades)
 Some vents become inactive if there is no Hydrogen
Sulfide available
 Eruptions can spill out lava killing organisms at vents
 New vents die out and appear regularly