Slide 1: Sea Floor Features
The Topography of the Ocean Floors
Slide 2: Hypsographic Curve
•Distribution of elevations and depths on Earth •Avg elevation= 2760 feet •Avg. depth = 12,451 feet
Slide 3: The Misconception…
• Earth’s crust is one solid layer • Like an M&M
Slide 4: Reality
Slide 5: The Misconception…
• The ocean is deepest in the middle rt Pa st pe ee D
Slide 6: The Misconception…
• The ocean floors are flat and featureless
Slide 8: Bathymetry
• The discovery and the study of the ocean floor contours
Slide 9: Sounding, The Early Years
Measured to a depth of 4,893 m (16, 054 ft) or roughly
3.04 mi!
Slide 10: Improvements- Sound
Side Scan Sonar
Echo Sounding
Slide 11: Improvements- Satellites
Slide 12: Submersible
• Submarine or equipment used to go under water
– Ex: Alvin
Slide 15: Continental Margins
• Continent extends into ocean • Granite Crust
Slide 16: Two Types
• Active
– Tectonically active – West coast
• Passive
– Tectonically inactive – East coast
Slide 17: Factors shaping land today?
•What shapes the coasts today?
–Waves –Storms –Wind
•Uniformitarianism
–Forces always present
•Catastrophism
–Catastrophies
How could these factors have affected the continental crust underwater?
Slide 18: The Sea Is Not On The Level…
•Fluctuations of sea level exposed and covered land •Continental shelf extends about 130 m below sea level •Level of sea at last ice age = 130 m below present
–Coincidence?
Slide 20: More on Sea Level
•Rock exposed at last ice age •Cave formed •Filled with water after sea level rise •Attraction for divers
Slide 21: Deep Ocean Basins
Slide 22: Abyssal Plains
•Flat •More in Atlantic •Covered by sediments •Up to 3,300 feet deep
Slide 23: Mid-Ocean Ridge
Slide 24: Formation of New Sea Floor
Slide 25: Hydrothermal vents or Black Smokers
• Near mid-ocean ridges • Release heat and chemicals
Em it S
ulfi des =
Bla
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mo ke
rs
Slide 29: New land forms Lava
pushed up
Older islands move with tectonic plate
Slide 31: au i M
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l Is
s nd a aw i ai
H
u O ah
Ho tS PL A TE
pot
DIR EC TIO N
Slide 32: Seamounts and Guyots
That’s Ge-o
Slide 33: Trenches and Island Arcs
•Trench is a deep depression in the sea floor •Occur at subduction zones •Islands form adjacent
Slide 35: Music by IZ
Iz Over the Rainbow: A Hawaiian Tribute Israel Kamakawiwo'ole
