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59 Cards in this Set
- Front
- Back
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Define Crust
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-Earth's outermost layer
-Rigid rock of continents and ocean florrs |
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How thick is the ocean floor?
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5-7km
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Which is denser, the ocean floor or the continental crust?
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Ocean floor
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How thick is the continental crust?
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30-100km thick
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What elements are the ocean floor composed of?
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-High in Magnesium, Calcium, Iron
-Lower in Silicon (In comparison to continental crust) |
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What element does the continental crust contain more then the ocean floor?
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Silicon
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Where is the mantle located? (Layers)
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-Under crust
-Above core |
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How thick is the mantle?
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3000 km
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What are the 2 parts of the mantle?
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-Lithosphere
-Asthenosphere |
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What state is the lithosphere in? (Solid, liquid, ect)
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-Solid
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What is the lithosphere composed of?
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-The crust and outermost solid mantle
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What are the characteristics of the asthenosphere?
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-The intense heat and pressure (From lithosphere above) causes it to act like a liquid
-Acts like a viscous liquid (Soft plastic) although it is made of solid mantle |
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What is the core?
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-Spherical center of the Earth
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What is the core's radius?
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-About 3500 km
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What is the core composed of?
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-2 Layers (Inner and outer)
-Inner -Mostly dense solid iron Outer -Liquid iron and nickel |
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What are the tectonic plates?
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-What the lithosphere is divided into
-Floats on the liquid-like asthenophere |
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What is the continental drift theory?
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The theory that argues that the continents have moves slowly since Earth formed and were once joined in a landmass called Pangaea
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Define paleoglaciation
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The extensive periods in which glaciers covered most of the continents
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Define Mid-Ocean Ridges
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-Undersea mountain range found by divergent boundaries
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What is the process of sea-floor spreading?
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- The widening of sea floor at mid-ocean ridges
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Define ocean trenches
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Trenches formed in the sea floor when 2 tectonic plates converge
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What occurs at the ocean trench?
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The sea floor is recycled back in to the mantle
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Explain the theory of plate tectonics
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-States that the lithosphere is divided into 12 large sections (Plates) and about 20 smaller ones
-These tectonic plates float on the more dense liquid-like asthenosphere -Each plate moves in a different direction relative to the African plate |
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What are the 3 boundaries?
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-Divergent
-Convergent -Transform |
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What is a divergent boundary? What occurs there? Along there?
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-The point where 2 plates move away from each other
-Creates shallow valleys or rifts -Most rifts are undewater (Mid ocean ridges) -Shallow earthquakes and small volcanoes occur along these boundaries |
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What is a rift valley?
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Something that occurs when a divergent boundary cuts across land
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What is a convergent boundary? What occurs there?
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-The point where 2 plates moving towards each other collides
-Sometimes the surface of one plate is scraped up creating mountains -Sometimes one plate is pushed beneath the other creating deep ocean trenches |
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What is the subduction zone?
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The subduction zone is the location where 2 plates overlap.
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What occurs at oceanic-oceanic convergent boundaries?
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-Creates islands
EA: Philippines |
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What occurs at oceanic-continental convergent boundaries?
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-Creates deep ocean trenches and parallel mountain chains
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What occurs at continental-continental boundaries?
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-Creates inland mountain ranges
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What is a transform boundary? What occurs there?
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-A boundary where plates move past each other in opposite directions
-Seen as strike-slip faults (Plates are moving on either side of the fault line in opposite directions) - Often causes earthquakes (Not smooth) |
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What is Mantle convection?
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-The convection currents within the mantle
-Hot mantle rises at one place, cools then falls down at another. This creates the convection currents -Friction between the mantle and lithosphere caused by convection currents moves the crust along |
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What is ridge push?
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-Hot mantle rises, heating the crust until it expands and floats higher. This creates a ridge and eventually the thin crust at the top of the ridge cracks, Magma rises up the crack and cools, wedging between the plates and pushing them.
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What is Slab Pull?
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The pull that results from the oceanic plate descending into the mantle. The convection currents in the mantle causes the plate to be pushed further in the mantle. About 700km down the temps and pressure softens and recycles the plate back into the mantle.
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Volcano
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A crack in the lithosphere where magma and gases reaches the surface.
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Hotspot
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-Small regions of very hot mantle
-Thought to be heated by radioactive materials -Creates very hot columns of rising mantles -Forms volcanoes as it bulges and cracks through the lithosphere |
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Volcanic belt
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-Chain of inland volcanoes
- Is created parallel to a oceanic-continental convergent boundary |
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How is the volcanic belt/arc formed?
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-Oceanic continent subducts under continental crust
-Water from oceanic continents turns into steam from heat and rises up -Steam lowers melting point of mantle -Mantle melts into lava -Follows cracks left by stress from subduction and follows it to the surface -Volcano |
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Volcanic island arc
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-Line of volcanic island
-Created on an overiding oceanic plate parallel to an oceanic-oceanic convergent boundary |
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Earthquakes
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-Vibrations through Earth's crust
-Caused by volcanoes and movement along plate boundaries (Tectonic activity) |
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Fault
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-Displacement of the lithosphere created by the movement of tectonic plates
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Focus
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Source of an earthquake within the lithosphere
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Epicenter
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Found directly above the focus on the surface
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Shallow Focus
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-0-70 km depth of focus
-Focus found in crust |
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Intermediate focus
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-70-300 km depth of focus
- Focus found within subduction zone |
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Deep-focus
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-300-700 km depth of focus
-Focus found within mantle |
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Seismic waves
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-Mechanical waves or vibrations in the Earth
-Ways Earthquakes transmit mechanical energy -2 types, body and surface |
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Body waves
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-Travels through a medium
-Earthquakes cause 2 types of body waves: Primary and Secondary |
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Primary Waves
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-Compression waves
-Particles in the medium vibrates backwards and forwards along the path of the wave - Can travel through all states -Goes through all layers |
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Secondary waves
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-Shear waves
-Particles in the wave vibrate perpendicular to the direction to the wave -Travels more slowly in comparison to P waves -Can only travel through solid rock |
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Surface waves
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-Travel waves along the outside of the Earth
-Causes the most destruction -Created when body waves reach the surface -Travels more slowly then body waves -Range is a few hundred km -Motion decreases significantly with depth |
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What are some indirect observations that provide clues to Earth's interior?
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-Measuring the magnetic fields of the layers of lava flows (Age of rocks)
-Measuring local strength of gravity allows you measure the density of the material below (Denser higher gravity) -Seismic waves (Speed and direction of waves changes as they go through different types of rock) |
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What evidence supports the theory of Pangaea?
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-Jigsaw fit (Shapes of continents fit)
-Fossil finds (Identical fossils, different continents) -Matching mountains (Similar mountains across continents + coal found in Antarctica) |
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What are erratic straitions?
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-When the glaciers scrape the ground below as they move (Makes lines indicating the direction of their movement)
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What are the sources of Earth's interior heat?
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-Heat left over from creation
- Radioactive decay |
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What 2 pieces of evidence supports sea floor spreading?
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-Radioactive dating
-Magnetic striping |
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What causes the extra heat at hotspots?
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Radioactive material decay
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What is the Hydroplate theory?
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Pressure of granite caused subterranean waters to gush out a supersonic speed, lubricating the bottom of the plates with water, causing move (Continental drift)
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