推 superemery:3是說地球上的iridium在隕石撞擊後被散佈在空中 12/16 01:02
→ superemery:事實上大部分的iridium是隕石帶到地球上的 12/16 01:03
最後一題的答案是124
但我覺得2很奇怪...(我選134)
希望大家可以指點迷津，謝謝!
There have been many attempts to explain the causes of mass extinctions.
●
●
●
Answer choices
○1. Asteroid impacts, evolutionary developments, and changes in Earth' s
climate and in the
Proofread By Miffy and Alex Page: 447 / 493
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.
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 114.45.176.43