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STUDY GUIDE
MARINE GEOLOGY
1. The Earth has layers because:
Density:
Denser materials sunk
Lighter materials rose
2. Why are there oceans on our planet?
Oceanic crust is denser than continental crust and therefore sinks lower into the
mantle. 1000s of years of rain filled in the depressions made by the lower oceanic
crust.
3.
The three layers of earth are the crust, mantle, and core.
4.
Earth’s core contains iron and nickel, making it a giant magnet.
5.
What are the two types of crust that make up Earth?
Oceanic and continental
6.
The process by which the ocean floor is extended is called
Sea floor spreading.
7. What is a crack that forms between two plates as they move apart?
ridge
8. The downward movement of a plate into the mantle is called
subduction.
9. In 1912, Alfred Wegener introduced the Continental Drift Theory.
10. Fossil evidence supports the theory of continental drift because:
Fossils of the same plants and animals are found on continents separated by oceans. The
continents had to have been connected.
11. How are subduction and sea floor spreading related?
They are a balanced process of creating new sea floor (sea floor spreading) and recycling
old sea floor (subduction)
12. Contrast the two types of crust on our planet?
Oceanic- Denser, younger, thinner
Continental- Lighter, older, thicker
13. How do we know that our earth has layers?
Evidence comes from looking at seismic waves
14. For each of the following theories list the evidence that supports them:
Continental drift- Same fossils and geologic features on unconnected continents,
Coastlines fit like a puzzle
Sea floor spreading- Sea floor age increases away from the ridge, magnetic
flipping is recorded like a mirror image on either side of the ridge, Sediment thickness
increases away from the ridge
Plate tectonics- Continental drift and sea floor spreading
15. Why do we think that the plates move?
Convection currents in the mantle (caused by heating of the mantle by the core) rise up
and then drag the plates with them as they move
16. How are passive margins different from active margins?
Passive- Wide continental shelf, less steep slope, no seismic activity
Active- Narrow shelf, steep slope, seismic activity
17. What is the force that moves the crustal plates?
Convection currents
18. List features of the ocean floor moving from the shoreline to the deep ocean.
Shelf, slope, rise, abyssal plain, guyots and seamounts (ridges and trenches also)
19. What direction are converging plates moving?
Towards each other
20. What direction are diverging plates moving?
Away from each other
21. What are the stages of our planets formation?
Heating, layers forming, cooling
22. Where did the water in our oceans come from?
Water: comets, volcanoes, rock and then water vapor condensing and raining for
thousands of years
23. Describe interesting facts about hydrothermal vent communities?
Do not rely on sunlight for food chain
24. Do we have a net increase in crust on our planet? Why or why not?
No. Although sea floor spreading is constantly creating new ocean crust, it is also being
recycled by subduction