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5. In paragraph 2, why does the author include the information that 105 tons of water flow through the Amazon river per second? ○To emphasize the great size of the volume of water that seems to have flowed through Mars’ outflow channels
○To indicate data used by scientists to estimate how long ago Mars’ outflow channels were formed
○To argue that flash floods on Mars may have been powerful enough to cause tearshaped “islands” to form
○To argue that the force of flood waters on Mars was powerful enough to shape the northern volcanic plains
6. According to paragraph 2, all of the following are true of the outflow channels on Mars EXCEPT: ○They formed at around the same time that volcanic activity was occurring on the northern plains.
○They are found only on certain parts of the Martian surface.
○They sometimes empty onto what appear to have once been the wet sands of tidal beaches.
○They are thought to have carried water northward from the equatorial regions.
Paragraph 3: Some scientists speculate that Mars may have enjoyed an extended early Period during which rivers, lakes, and perhaps even oceans adorned its surface. A 2003 Mars Global Surveyor image shows what mission spets think may be a delta—a fanshaped network of channels and sediments where a river once flowed into a larger body of water, in this case a lake filling a crater in the southern highlands. Other researchers go even further, suggesting that the data provide evidence for large open expenses of water on the early Martian surface. A computergenerated view of the Martian north polar region shows the extent of what may have been an ancient ocean covering much of the northern lowlands. The Hellas Basin, which measures some 3,000 kilometers across and has a floor that lies nearly 9 kilometers below the basin’s rim, is another candidate for an ancient Martian sea.
7. All of the following questions about geological features on Mars are answered in paragraph 3 EXCEPT: ○What are some regions of Mars that may have once been covered with an ocean?
○Where do mission scientists believe that the river forming the delta emptied?
○Approximately how many craters on Mars do mission scientists believe may once have been lakes filled with water? ○During what period of Mars’ history do some scientists think it may have had large bodies of water?
8. According to paragraph 3, images of Mars’ surface have been interpreted as support for the idea that ○the polar regions of Mars were once more extensive than they are now
○a large part of the northern lowlands may once have been under water
○deltas were once a common feature of the Martian landscape
○the shape of the Hellas Basin has changed considerably over time
Paragraph 4: These ideas remain controversial. Proponents point to features such as the terraced “beaches” shown in one image, which could conceivably have been left behind as a lake or ocean evaporated and the shoreline receded. But detractors maintain that the terraces could also have been created by geological activity, perhaps related to...
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This note was uploaded on 09/17/2013 for the course LANGUAGE 13DL208 taught by Professor Wang during the Fall '13 term at East China Normal University.
- Fall '13