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Ch. 7 guide

Earth science

QuestionAnswer
What rocks make up the ocean floor and continental crust? Basalt= ocean floor. Granite= continental crust.
What happens during convection? During convection currents, the middle mantle is turned and heated, until the magma has an opening to come out.
What were Wegener's 3 pieces of evidence for continental drift? Landforms, fossils, climate
What are the 3 pieces of evidence that prove sea-floor spreading occurs? Molten material, magnetic stripes, and drilling samples
Describe the mantle, outer core, and the inner core. The mantle is 67% of Earth's mass, 2,900km thick, and temps. from 1,000-3,700 deg C. Crust is less than 1% of Earth's mass, 5-100km thick, and temps. from 0-1,000 deg C. Core is 33% of Earth's mass, radius of 3,430km, and temps. from 3,700-7,000 deg C.
How do the shapes of the present day continents support continental drift? The shapes of the continents today support continental drift because the the animals the were found in places are now separated by oceans, animals can't swim that far. Also, glacier scratches found on rocks in S. Africa proves that S. Africa was once in c
How do geologists observe Earth's interior? They send out seismic waves out to see the inside of the Earth. The seismic waves tell them what material that layer is made up of and how many layers there are.
Why did scientists reject Wegener's idea of continental drift? From the calculated strength of the rocks, it did not seem possible for the crust to move in that way.
List the order of the layers starting with the outermost layer. Crust,(oceanic crust, continental crust, lithosphere), mantle,(upper mantle, convection currents, asthenosphere, lower mantle), outer core, and inner core.
What is Pangaea? Pangaea is a huge, giant piece of land. A huge land mass.
When scientists obtained rock samples by drilling on the sea floor, what did they discover? They discovered that the crust is to thick to drill through to get to the mantle.
What are tectonic plates? Tectonic plates are pieces of lithosphere that move around on top of the Asthenosphere.
Explain what happens to density, temperature, and pressure as the depth beneath the Earth increases. The deeper you go into the Earth, the temp., pressure, and density increases.
What is the theory that states that the plates are in constant, slow motion? The theory is called plate tectonics.
Which major ocean is shrinking? Why?(Think back to video clip.) The Pacific ocean is shrinking because the Atlantic Ocean is making more new land faster than it can destroy the old land. Also, the continents are pushing together to form one giant land mass again. Because, there are so many trenches around the plates.
Old ocean crust is more dense than new ocean crust because it is farther away from the_________. Old ocean crust is more dense than new ocean crust because it is farther away from the center.
Where does the molten material rise out of and harden? The molten material rises out of the mantle and hardens at the bottom of the ocean.
If subduction does not occur on the ocean floor, what will happen to the ocean floor? If this process doesn't happen, the ocean floor will become like a sinkhole and no new land will form.
Explain the theory of continental drift. This is the Hypothesis that the continents were once a single landmass, broke up and drifted to their present locations.
What is the mid-ocean ridge? The mid ocean ridge is a place where sea-floor spreading takes place. They are under water mountain chains that run through Earth's ocean basins.
Which type of boundary would you find the mid-ocean ridge? You would find a divergent boundary.
What is created when 2 pieces of continental crust collide at a convergent boundary? This is called continenal-continenal collision/ boundary.
Compare the ages of the oceanic crust at the middle of the mid-ocean ridge, and away from the middle. The crust that is closer to the mid-ocean ridge is newer compared to the crust farther away from the mid-ocean ridge.
What is created along a divergent boundary? New sea floor forms at a divergent boundary.
What are faults? What stresses occur at faults lines? A fault is the surface along which rocks break and slide past each other. The stresses that occur are called compression and tension.
Which layer of the Earth spins giving us a magnetic field? The inner core spins to give us the magnetic field.
What is the main cause of the movement of the plates? Changes in density within the asthenosphere.
What happens along a transform boundary? Two tectonic plates slide past each other horizontally.
What is GPS? What is it used for? This means Global Positioning System. GPS is used to measure the rate of tectonic plate movement.
Explain the process of sea-floor spreading. New oceanic Lithosphere forms as magma rises toward the surface and solidifies. As the tectonic plates move away from each other the sea floor spreads apart and magma fills in the gap. New crust forms and old crust gets pushed away from the ridge.
Created by: Katie Ratcliff