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Geology of the Oceans
Did we always have oceans?_____
• Have they changed ?___________
• Oceans formed between 4.2-3.8 billion years ago
– Water vapor escaping from crust condensed on
surface
–
http://www.youtube.com/watch?v=hwVU0-2Qnso&safety_mode=true&persist_safety_mode=1
After the ocean formation
• 3.6 billion years of simple cells
(prokaryotes)
• 3.4 billion years of stromatolites
demonstrating photosynthesis,
SNOWBALL EARTH
• 2 billion years of complex cells
(eukaryotes)
• 1 billion years of multicellular life,
Snowball earth
Continental Drift: Creation of
oceans
Do oceans change?___
how?_____________
___________________
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World Ocean
Covers 70.8% of Earth’s surface
Four main basins—Pacific, Indian, Atlantic, Arctic
1. Which ocean is the largest?_______
2. Which ocean is between North America and
Europe?________
• 3. Which ocean is
Bordered by Africa,
Australia, India?
______________
Geology of the Oceans
• Continental crust vs. Oceanic crust: What is the
difference?_______________________
Continental Drift
• Magma & convection currents
drive continental movement
• Erupting magma
– Midocean ridges
– ridge systems
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Subduction zones:
__________________
Seafloor spreading:
__________________
Mid-Ocean Ridges
Ocean Basin
• Abyssal
Plains and
Hills
• Seamounts
• Ridges and
Rises
• Trenches
– Island arcs
– Marianna
Trench
Evidence for Continental Drift
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Fit of the continental boundaries
Distribution of earthquakes
Temperature of the sea bottom
Age of rock samples from the seafloor:
young/old
• Analysis of core samples drilled through the
ocean sediments.
What is on the bottom of the
ocean?
Rift Communities
• Rift communities, or deep-sea vent
communities
• 1977
• Food webs in
absence of sunlight
Composition of Sea Floor
• Hydrogenous Sediment
• Biogenous Sediment
– Calcareous ooze
– Siliceous ooze (glass)
• Terrigenous Sediment
– mud
• Cosmogenous Sediment
– Iron rich
Aliens of the deep
• Watch the video and list any organisms that you can
identify and what criteria you used to identify them.
Work in groups 2-4