TPO 15 MASS EXTINCTIONS - 英檢

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There have been many attempts to explain the causes of mass extinctions.
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Answer choices
○1. Asteroid impacts, evolutionary developments, and changes in Earth' s
climate and in the
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positions of the continents have all been proposed as possible causes of mass
extinctions.
○2. Researchers have observed 26-million-year cycles in extinction rates of
a number of fossil
groups that could all be attributed to the same cause.
○3. According to the Alvarez hypothesis, much of the iridium originally
present on Earth was
thrown into the atmosphere as a result of an asteroid impact that also caused
a mass extinction.
○4. The unusual distribution of iridium on Earth and the presence of craters
and heat-shocked
quartz are central to the theory that an asteroid impact caused the late
Cretaceous event.
○5. The collision between Earth and a large asteroid resulted in massive
damage and
generated enough heat to cause irreversible changes in Earth' s atmosphere.
○6. There was a particularly large mass extinction that occurred around 250
million years ago
at the end of the Permian period, whose cause could not be determined.

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