Download Plate Tectonics Study Guide: Answer key

Study Guide for Chapter 1. Plate Tectonics
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✓ Know the 4 layers of the Earth and be able to describe them (location,
consistency, temperature, pressure, density)
➢ Crust: Outer most layer of the Earth, surrounds the earth like an
Egg Shell ;2 types
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Continental Crust: Land, part of the Earth that we can see,
less dense than oceanic crust
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Oceanic Crust: Under the ocean, more dense than continental
crust,
➢ Mantle: largest layer of earth. Paste (peanut butter) like molten
material. Warmer than the crust, but cooler than core:
Convection currents take place here
➢ Outer Core: Hot liquid metal, more dense than the mantle, but less
dense than inner core
➢ Inner Core: center of the Earth, SOLID in spite of intense heat
because of pressure. Like a magnet
Lithosphere: made of crust and upper mantle. Another name for plates
Asthenosphere: soft upper to mid mantle. Exact place where convection currents
take place.
✓ Who was Alfred Wegener: Scientist who came up with the idea of
continental drift
o Explain his “Theory of Continental Drift”: States that the Earth
continents were once joined into one large supper continent. Over
time drifted apart
o What evidence did he have to support it (3 types): be able to explain
each type of evidence: 1) fossils of mesosaurs found in Africa and
South America, 2) Rocks in Brazil match Rocks in Africa, 3) Ice
scraping in Africa (showed Africa used to be really cold.) 4)
Continents fit together like a puzzle.
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o Why did no one believe him: He could not explain HOW or WHY the
continents moved
o Describe new evidence that lead to today’s Theory of Plate Tectonics
Sea Floor Spreading: Found mid ocean ridges and trenches. Rock near
center of mid ocean ridge was younger than rock near trench.
o Know these terms
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Pangaea: Name of supercontinent that Wegener thought
existed 250 million years ago.
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Sea-floor spreading: Rock near mid ocean ridge is younger
than near trench. As new rock is created it pushes old rock
away from the ridge
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Mid-ocean ridge: Mountains found on the ocean floor. Place
where sea floor spreading occurs. Oceanic-oceanic divergent
boundary
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Ocean trenches: deep areas in the ocean where old dense
oceanic crust is subducted back into the asthenosphere.
Involves at least 1 oceanic crust and another crust in
convergent boundary
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Convection current-be able to apply to the mantle: Heated less
dense material will rise and come out of a mid ocean ridge. As
the rock cools it will become more dense and will eventually sink
in a trench back to asthenosphere and the process cycles
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Theory of Plate Tectonics : Outer surface of Earth is made
of plates called the lithosphere, these plates slide on the
asthenosphere which is soft and tar like.
Types of Boundaries
✓ Convergent Boundaries- know what they are, and land forms associated with
them plates come together
o Oceanic-oceanic boundaries Land forms: Trench, Island Arcs or
volcanic islands. Crust is destroyed here
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o Oceanic-continental boundaries Land forms: trench, coastal
mountains and volcanoes. Crust is destroyed here
o Continental-continental boundaries: Mountain Range: Rocky
Mountains
✓ Divergent Boundaries
o Oceanic-oceanic: Mid ocean Ridge: also known as a spreading center.
Place where new crust is created.
o Continental-continental: Rift Valley will have valley with volcanoes.
Will eventually turn into a mid ocean ridge
✓ Transform Boundaries: Place where plates scrape past each other. Crust is
NOT created or destroyed here
Land forms to know
➢ Mountains: created when continental crust converge with other crust. No
volcanoes when 2 continental crust come together
➢ Coastal mountains: Mountains near coast, associated with Oceanic
Continental convergent boundary These mountains will have volcanoes
➢ Hot spot: found away from plate boundaries. Help scientist study plate
movement
➢ Arc Islands: chain of volcanic islands that run parallel to a trench
➢ Volcanoes: place where molten material seeps through the crust
➢ Rift Valley: found a divergent boundaries, esp land masses