地质学
Rift
1.What is the lecture mainly about?
- A. The recent discovery of an unusual tectonic plate
- B. The effects of underwater riffs on plate boundaries located on land
- C. The development of a new technology for studying rifts located on land
- D. The process by which tectonic plates are separated
2.Why does the professor mention Iceland?
- A. To support the claim that rifts occur wherever volcanoes occur
- B. To point out that Iceland is located on a plate boundary
- C. To give an example of a rift area that is located on land
- D. To give an example of an extraordinary active rift system
3.What unexpected discovery did scientists make while studying the rift event in East Africa?
- A. Rifts can widen more quickly than previously thought.
- B. Some magma deposits lie closer to Earth surface than geologists realized.
- C. Volcanic activity is not necessary for rift formation.
- D. Volcanic activity along land rifts is different from activity along underwater rifts.
4.In the lecture the professor discusses an event that occurred along a rift in East Africa. Place the stages of this event in order.
| A. Molten rock flowed into the rift and widened it. | |
| B. There was a brief period of inactivity. | |
| C. Seismic activity began 30 kilometers south of the northern volcanoes. | |
| D. There was a series of earthquakes near the northern volcanoes. |
5.According to the professor, what may eventually occur at the location of the recent rift event in East Africa?
- A. Two tectonic plates will merge.
- B. A deep basin will form.
- C. A new fissure will open.
- D. Underground earthquakes will become more frequent.
6.What does the professor imply when he says this:
- A. The East Africa Rift System is much larger than previously thought.
- B. “East Africa Rift System” is an obvious name for the system.
- C. The East Africa Rift System is not actually a system.
- D. Not all of the East Africa Rift System is located in Africa.
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