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The Earth’s Oceans and Plate Tectonics. Oceanography Unit #1. Our Earth. Earth is between 5.0 and 7.0 billion years old . Crust Mantle Outer core Inner core. The Earth’s Crust. Asthenosphere – an area of weakened crust and molten upper mantle. - PowerPoint PPT Presentation
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The Earth’s Oceans and
Plate Tectonics Oceanography Unit #1
Our Earth Earth is between 5.0 and 7.0 billion years old. Crust Mantle Outer core Inner core
The Earth’s Crust Asthenosphere – an area of weakened crust
and molten upper mantle. Lithosphere – the rigid hardened crust.
Crustal types: Oceanic Crust – found beneath the ocean
basins Continental Crust – found beneath the
continents and margins
Crustal Comparsions
Earth’s Hydrosphere Oceans are approx. 4.0 billion years old. Oceans cover approx. 71% of the earth’s
surface.
Water? Oceans = 97.22% Glaciers = 2.15% Ground water = .62% Atmosphere, lakes, rivers, etc. = <.01%
The Ocean Basins
Southern Ocean – combination of the most southern Pacific, southern Atlantic, and southern Indian; surrounding Antarctica.
Ocean Topography Continental shelf – submerged edge of the continent;
most biologically active. Continental slope – descends from shelf down to the
deep sea-floor. Continental rise – sediments that accumulate at the
slope’s base. Abyssal plains – most of the ocean’s floor;
avg. depth = 4.0 km. Seamounts – submarine volcanoes Trenches – found at base of slope; depth >6.0 km.
Mid-Ocean Ridge System“Spreading centers”; crustal expansion.Largest geographical feature on planet.Total length is over 65,000 km.
Plate Boundaries1. Divergent:• Two or more plates are directed away from each other.• Mid-ocean ridge system• Numerous volcanic eruptions and earthquakes.• Volcanic islands such as Iceland, Azores, and Ascencion.
2. Lateral:• Two plates slip past each other.• San Andreas Fault (CA).• Numerous large earthquakes
Plate Boundaries1. Convergent:• Crustal plates are directed towards each other.
i. Two continental plates collide:• Build up of crust in to mountain ranges.• Himalayan Mountains
ii. One continental plate and one oceanic plate collide:• Creates subduction zones.• Japan Islands, New Zealand, Andes
Subduction Zone
Hotspots Areas where magma punches a hole in thin, weak
crust above; Stationary. Hawaiian-Emperor island chain:
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