Download ch7 answers to SG

1. What are the two types of crust or lithosphere? Oceanic and Continental
2. What did Wegener call the one large landmass before the continents drifted apart? Pangaea
3. Where does new oceanic lithosphere form? Mid Ocean Ridges
4. What is the evidence for sea-floor spreading? Magnetic Reversal
5. What is the liquid layer of the earth's core called? The Outer Core
6. What is the place where tectonic plates meet called? Boundary
7. What type of boundary is formed when plates collide? Convergent
8. What type of boundary is formed when plates separate? Divergent
9. What type of boundary is formed when plates slide past each other? Transform
10. What is the evidence for continental drift? Puzzle-like fit of the continents, fossils, ancient
climactic conditions, sea-floor spreading
11. The mantle has more magnesium than the crust, which makes it _______________? Denser
12. How does the density of the layers of the earth affect seismic waves? Seismic waves are slowed
and bent by different layers of different densities.
13. Volcanic mountains are formed when what reaches the surface of the earth? Magma
14. How is continental drift related to plate tectonics? No set answer – looking for student thought.
They are similar ideas.
15. Transform boundaries have more of which geological event? Earthquakes
16. What type of boundary creates a mid-ocean ridge? Divergent
17. What is compression? Stress caused by things being pressed together
18. What is tension? Stress caused by things being pulled apart
19. Mountains are pushed up at which kind of boundary? Convergent
20. Which layer of the earth does the lithosphere float on? Asthenosphere
21. When earthquakes happen what do they produce? Seismic Waves
22. As the sea-floor spreads at mid-ocean ridges, where are the newer rocks and the older rocks?
Newer in the middle, Older further away in both directions
23. When continental plates collide with oceanic plates, what happens? Subduction – the oceanic
plate subducts under the continental plate.
24. What type of fault occurs on a transform boundary? Strike-slip Fault
25. The core of the earth is divided into a liquid outer core and a solid inner core, but both are made of
what element? Iron
26. Thermal energy transfer is responsible for the convection currents in the asthenosphere because
heat causes the material to change. What quality changes
in the rock? Density
27. Lithospheric plates move over hot spots, so that molten material rises through the middle of the
plate. Which islands in the Pacific Ocean are on a hot spot? Hawaii
28. Does more dense or less dense material tend to rise? Less Dense
29. Describe the role of the asthenosphere in the movement of tectonic plates. No set answer – in
general, the asthenosphere transfers thermal energy to the surface by way of convection
currents. Convection currents in the asthenosphere are dense solid rock sinking through less
dense solid rock over a period of millennia, at a rate of a few centimeters per year.
30. If we could dig all the way to the center of the earth, would the rocks get denser or less dense as we
dug down? Denser
31. Tectonic plates forming a transform boundary may move only a few centimeters each year. Can
even this small movement affect people and communities
near a transform boundary? No set answer – In general, transform boundaries are the location
of most earthquakes, and earthquakes often affect people and communities in profound ways.