Term
| How much of the Earth's surface is covered by oceans? |
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Definition
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Term
| What are the major compositional layers of the Earth? |
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Definition
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Term
| What is the dominant rock type in the ocean crust? |
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Definition
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Term
| What is the dominant rock type in the continental crust? |
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Definition
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Term
| How do basalt and granite differ in terms of composition and density? |
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Definition
Basalt = thin and dense
Granite = thick and less dense |
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Term
| How is rock density associated with the location of ocean basins? |
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Definition
| The denser rocks form basins, which is deeper than the continental surface. Water flows downward and is held in these basins. |
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Term
| What is the lithosphere, the asthenosphere? How do they differ? |
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Definition
| The lithosphere is the crust and the top part of the mantle. It is brittle. The asthenosphere is the softer layer beneath the lithosphere which is "plastic" - it flows. |
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Term
| What is isostasy and how does it explain why there are mountains? |
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Definition
| Isostasy = an object will displace a volume of water equal to its own mass. Mountains are made of granite - less dense than the asthenosphere - they "float" in it. The bigger the chunk of land that is "floating" the taller the mountain because the more shows above the surface. |
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Term
| Describe seafloor spreading and how it produces the symmetrical magnetic reversal zones associated with divergent plate boundaries. |
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Definition
| Sea floor spreading is a process by which magma from beneath the ocean floor rises and pushes plates apart, forming a strip of new sea floor. Each new strip has a reversed magnetic field from the last. |
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Term
| Where are the youngest rocks found in the oceans? Why? |
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Definition
| At the very center of the ocean floor. These rocks are the newest formed from the magma force beneath the ocean floor. |
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Term
| What was Pangaea? When did it break apart? |
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Definition
| Pangaea was one large land mass before it broke into the continental pieces there are today. It broke apart about 180 million years ago. |
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Term
| How old is the ocean floor? Why isn't it older? |
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Definition
| 180 million years; because it only began forming after Pangaea broke apart. |
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Term
| If Earth is criss-crossed with divergent plate boundaries, then why isn't the Earth getting larger? |
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Definition
| Because there are also convergent boundaries. |
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Term
| Describe the different types of plate boundaries (divergent, convergent, transform). |
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Definition
| Divergent boundaries are when two plate pull apart in opposite directions. Convergent boundaries occur when two boundaries collide into one another. Transform boundaries are when two plates slide alongside and past each other in opposite directions. |
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Term
| How does the theory of plate tectonics explain the locations of volcanoes and earthquakes? |
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Definition
| Volcanoes and earthquakes form when convergent boundaries collide. (Smaller earthquakes can also occur in divergent boundaries and transform boundaries). |
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Term
| How does the theory of plate tectonics explain the seafloor age and the formation of magnetic reversal zones? |
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Definition
| The oceans are relatively young compared to the age of the Earth. This is because the oceans didn't start forming until after Pangaea broke apart 180 million years ago. Magnetic reversal zones can be explained by seafloor spreading. Sea floor spreading is a process by which magma from beneath the ocean floor rises and pushes plates apart, forming a strip of new sea floor. Each new strip has a reversed magnetic field from the last. |
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Term
| How does a linear chain of seamounts (volcanoes) support the idea of seafloor spreading? |
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Definition
| Hotspots are stationary sources of magma found beneath the Earth's surface. When magma rises and forms a volcano, the volcano eventually moves away from the hotspot as the plates shift. When magma rises again, a new volcano is formed over the hotspot, and this process repeats. The volcanoes get progressively older as they get further from the hotspot, proving this theory. |
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Term
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Definition
| Hotspots are stationary sources of magma found beneath the Earth's surface. |
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Term
| What are abyssal plains and why are they better developed in the Atlantic vs. the Pacific Ocean? |
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Definition
| Abyssal plains are very flat surfaces formed by very fine particles which settle and cover ocean crust irregularities. They are formed better in the Atlantic Ocean because it is not as deep as the Pacific Ocean. |
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Term
| What three major provinces make up the ocean floor? How do they differ? |
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Definition
| The continental margins are the shallow-water areas close to shore. Deep-ocean basins are the deep-water areas further from land. The mid-ocean ridge is a submarine mountain range. |
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Term
| Describe the difference between an active and a passive continental margin in terms of tectonic activity, plate boundaries, and associated ocean floor features. |
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Definition
| Passive continental margins are coasts that are not close to any plate boundary. There is no major tectonic activity here. (For example, the NJ Shore). Active continental margins are associated with convergent or transform plate boundaries. Tectonic activity is common. (For example: western South America). |
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Term
| How are submarine canyons formed? |
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Definition
| They are formed by large pieces of sediment carving the ocean floor over time, including landslides, etc. |
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Term
| How are subduction zones, volcanic arcs, and ocean trenches related to each other? |
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Definition
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Term
| Are hydrothermal vents the same as hotspots? Where are vents typically found? |
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Definition
| No, hydrothermal vents are sources of magma found within the mid-ocean ridge. |
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Term
| Where is most of the lithogenous sediment found and why? |
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Definition
| Most of it is found in the continental shelf, slope, and rise because they are denser than the air and therefore cannot be carried too far. |
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Term
| What are the major types of marine sediments? What are the sources of each? |
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Definition
| Lithogenous (derived from land); Biogenous (derived from organisms - plants and animals); and Hydrogenous (derived from water). |
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Term
| Which sediment type accounts for the greatest volume? Which covers the majority of the sea floor? |
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Definition
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Term
| How is lithogenous sediment classified? |
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Definition
| By the size of the grains.(Gravel, sand, mud). |
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Term
| Why is some lithogenous sediment (abyssal clays) found in deep-ocean waters far from its land source? |
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Definition
| Because they are very fine sediments which are carried by wind over farther distances. |
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Term
| Explain the processes that control the global distribution of siliceous and carbonate sediments. |
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Definition
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Term
| What is the origin (types) of biogenous sediment? (plants, animals, composition) |
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Definition
| Photoplankton (plant); Zooplankton (animal); Rock formed. |
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Term
| What is the definition of ooze? |
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Definition
| Ooze makes up 30% of biogenic sediment. |
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Term
| What is the calcite (carbonate) compensation depth? |
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Definition
| The depth in the ocean below which calcite (carbonate) readily dissolves. |
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Term
| How does water depth influence the type of sediment deposited there? |
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Definition
| Cold water tends to dissolve some shells on their way down, and some particles never make it below a certain point because they dissolve completely. |
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Term
| Why are manganese nodules primarily found in the Pacific Ocean? |
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Definition
| Because the sedimentation rate is very slow. |
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