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24 Cards in this Set
- Front
- Back
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Earths' Layers
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Chemically distinct, and took form during the differentiation stage of the Earth's history
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Crust Thickness:
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Under water: 5
Under continent: 40 Under mountain: 65 |
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Crust Composition:
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Ocean:
-Basalt, gabbro -Mafic -7 km/s -2.9 density Land -Granite -Felsic -6 km/s -2.8 |
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Hypsographic Curve
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70% of the mass is under sea level (Heavier)
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Mantle
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Made of olivine and pyroxene
Silicates: Iron and magnesium Density: 3.3 Properties and formation change with temperature and pressure (Upper mantle - melt; Lower mantle - Compact) |
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Core
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Iron, molten outer core
200 km thick *Huge drop in P velocity |
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Layering of Earth
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We layer the earth based on the physical properties of the earth
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Continent
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Rock above water
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Egg Analogy
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Brittle outer core, solid inner core
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Lithosphere Facts
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Lithosphere moves on the astenosphere
(Isostasy: Lithosphere floats based on density) Root of the lithosphere is embedded in the astenosphere |
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Low Velocity Zone
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Low velocity because of partial melt (astenosphere)
100-200 km We know about the partial melt because of seismic waves |
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Transition Zone
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410-660 km
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Boundaries
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1. Divergent
2. Convergent 3. Transform at each*: Create/destroy, volcanism/earthquakes, type of force |
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Divergent Boundaries
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-TENSIONAL
-NORMAL FAULTS Ocean: Rift, crack like valley at mid-ocean ridge, sea-floor spreading, creation of lithosphere, volcanism and earthquakes, extremely hot b/c of magma Continent: Down-faulted rift valleys |
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Examples of Divergent Boundaries
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Mid-Ocean Ridge (650000 km long)
Mid-Atlantic Ridge Great Rift Valley Rhine Valley East Pacific Rise (longest spreading) |
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Passive vs. Active Continental Margins
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East Pacific, Mid-Atlantic, South America (active)
Coast lines (passive) |
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Black Smokers/Hydrothermal vents
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500-600 degrees Celsius
Underground spring/geyser Found near volcanically active regions |
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Mid Atlantic Ridge
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Mid-ocean ridge, divergent boundary, part of longest mountain range in the world, surfaces above in Ireland
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Convergent Boundaries
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-Subduction, one plate sinks beneath the other, lithosphere goes into astenosphere and this is an example of destruction
-Trenches are produced -100 km wide, 10 km below sea level -Volcanism, earthquakes (worst in multitude) |
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Convergent Types:
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Ocean-Ocean: Volcanic island arc, trenches, earthquakes
Ocean-Continent: Volcanic mountain belt (Felsic, explosive, Mt. Helena, Cascades), earthquakes Continent-Continent: Sature zone, high mountain chains (Himalayas) |
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Transform Boundary
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Motion slips by each other horizontally along a transform fault
No volcanism, no destruction./creation Land: San Andreas, right-lateral Sea: Offsetting of mid-ocean ridges |
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Evidence for Plates
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1. Earthquakes
2. Volcanoes 3. Subduction 4. Magnetic bands & sea-floor spreading |
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What drives motion?
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Ridge-push: Gravity causes ridge to push on lithosphere
Slab-pull: Subduction |
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Intra-Plate Hot-Spots
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Yellowstone, Hawaii
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