Term
| What force causes the movement of Earth's plates? |
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Definition
| Convection Currents in Earth's mantle. |
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Term
| What kind of boundary causes two plates to pull apart? |
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Definition
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Term
| What was Wegener's idea about what happens during continental drift? |
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Definition
| The continets move around. |
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Term
| In what areas of the ocean does subduction take place? |
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Definition
| deep-ocean trenches - the older, denser oceanic plate will subduct and be recycled into the mantle |
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Term
| What happens to new oceanic crust at a mid-ocean ridge? |
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Definition
| It moves away from the ridge as new material comes up. It formes new mountain ridges under the water. |
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Term
| In sea-floor spreading, where is new crust added? |
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Definition
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Term
| What evidence did Wegener use to form his hypothesis of continental drift? |
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Definition
| Land features, like mountains, matched up, fossils were found widely separated, climate evidences - like the evidence of glaciers in now warm areas |
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Term
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Definition
| a tropical fern-plant. It's fossils were found in widely separated areas (many places where it wouldn't have survived) |
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Term
| What does Pangaea mean in Greek? |
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Definition
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Term
| What was the name for the small submarine that searched the ocean floor in the 1980s? |
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Definition
| Alvin (wasn't a chipmunk, though :) ) |
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Term
| What happens when an ocean plate hits a continental plate? |
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Definition
| The ocean plate will subduct (go down) because it is colder, older, and denser. |
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Term
| What was the name of the theory that Wegener proposed in the early 1900s? |
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Definition
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Term
| How old are the oldest parts of the ocean floor? |
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Definition
| About 200 million years old |
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Term
| What do we call a divergent boundary on land? |
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Definition
| We call it a RIFT VALLEY. The most widely known one is the Great Rift Vally in Africa. |
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Term
| Why did most geologists reject Wegener's ideas when he first proposed them? |
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Definition
| 1. Wegener had no way to prove how it happened. 2. They didn't want to start over. 3. Some said the continents fit "too" perfectly. |
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Term
| What is currently happening with the size of the Atlantic Ocean? |
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Definition
| The Atlantic Ocean is currently getting bigger. There are not many trenches in the Atlantic to swallow up old rock and recycle it. The mid-ocean ridge is making new rock quicker than it can be recycled. |
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Term
| What feature is made is made when an oceanic plate hits a continental plate? |
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Definition
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Term
| What happens to the density of the ocean floor as it moves away from a mid-ocean ridge? |
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Definition
| It gets DENSER as it gets older and colder. |
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Term
| Is Pangaea the only supercontinent to have ever existed? |
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Definition
| NO! Over time there have been many others. |
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Term
| What process adds new land to the ocean floor? |
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Definition
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Term
| What is the mid-ocean ridge? |
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Definition
| An underwater mountain range |
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Term
| What is a deep-ocean trench? |
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Definition
| An underwater valley where subduction is occurring. |
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Term
| What happens at a convergent boundary? |
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Definition
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Term
| What happens at a transform boundary? |
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Definition
| Two plates slide past each other without much up or downward movement. A crack is formed. |
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Term
| What is true of the ages of the rocks on the ocean floor? |
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Definition
| The rocks at the mid-ocean ridge are younger. The rocks far from the mid-ocean ridge were a lot older. |
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Term
| Where is crust more dense on the ocean floor? |
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Definition
| The crust that has cooled that is far from the mid-ocean ridge is denser. |
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Term
| Which ocean-Atlantic or Pacific-has more deep-ocean trenches? |
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Definition
| The Pacific has A LOT more trenches. That is why the Pacific is getting smaller. |
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Term
| Where does sea-floor spreading occur? |
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Definition
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Term
| Why was it unlikely that Mesosaurus swam back and forth across the ocean? |
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Definition
| 1. He was a freshp-water animal-salt water would have killed him. 2. He needed to breathe air. 3. He was small - 71 cm - and would have been eaten. 4. He wasn't built for a long swim. |
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Term
| What were the six pieces of evidence that Wegener noticed that supported Continental Drift? |
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Definition
1. coal beds in North America and Europe match up
2. Puzzle-like fit of the continents
3. Glossopteris fossils in cold areas
4. Mesosaurus fossils on widely separated continents.
5. Lystrosaurus fossils on widely separated continents.
6. Glacial deposits in now warm areas |
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Term
| Why are the oldest parts of the oceans NO OLDER than about 200 million years old? |
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Definition
| They slowly move across the ocean floor until they reach a subduction zone and are then subducted and recycled. |
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Term
| Where are the magnetic stripes located? |
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Definition
| On the ocean floor. Both sides of the ocean floor match since the mid-ocean ridge splits the middle layer and pushes half of each of it in opposite directions. |
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