首页
登录
职称英语
Something very unusual happened about 80,000 years ago, as Earth’s last ice
Something very unusual happened about 80,000 years ago, as Earth’s last ice
游客
2023-08-14
11
管理
问题
Something very unusual happened about 80,000 years ago, as Earth’s last ice age was getting started. Sea levels that had been dropping for thousands of years—as more and more water became trapped in expanding glaciers(冰川)—suddenly rose, according to a new study. Then after a few thousand years, the levels fell again. Although the researchers haven’t found the cause of this phenomenon, they say the findings could force at least a partial rethinking of the mechanisms governing Earth’s climate.
For the past several hundred thousand years, our planet seems to have followed a fairly regular climate cycle. About every 100,000 years, kilometers-thick ice sheets form atop the northernmost reaches of North America, Europe, and Asia and extend well into the mid-latitudes. The ice sheets also tie up so much seawater that ocean levels can drop by over 100 meters. Then, after about 90,000 years, the glaciers retreat and land reappears, until the next ice age begins. The last ice age ended about 11,000 years ago.
Various researchers going back nearly a century have attempted to isolate the cause of the ice-age cycle. They have uncovered several factors —periodic changes in Earth’s orbit around the sun, for example—that seem to be in play. But so far no one has presented the definitive answer.
In the recently published Science, a team doesn’t so much solve the puzzle as reinforce the uncertainties about how the ice-age cycle behaves. What they’ve found is very strong evidence that when Earth should have been preparing for the last ice age, the seas rose.
The researchers found that sea level 80,000 years ago had rebounded to the point where it rose 1 meter higher than it is today. And it could have risen quite quickly, as much as 2 meters per century, says geochemist Jeffrey Dorale of the University of Iowa.
That suggests the glaciers were melting at a tremendous rate. Even half that rate would still be "a major finding," Dorale says. So it "has major implications for future concerns with sea-level change."
The study "shows persuasive evidence" for a surge in sea level about 80,000 years ago, says geologist Daniel Muhs of the U.S. Geological Survey in Denver. He says the findings help make a "powerful" argument for the phenomenon. Still mysterious, however, are other data, taken from Barbados and New Guinea, that also suggest rising sea level about 80,000 years ago but not nearly as much of a change. It means, Muhs says, "that there is much about interpreting the geologic(地质学的)record of sea-level variation that we still do not understand." [br] What happened when Earth’s last ice age was getting started?
选项
A、Water began to be trapped in glaciers.
B、Glaciers began to melt into water.
C、Sea levels suddenly rose.
D、Sea levels suddenly dropped.
答案
C
解析
第1段第1句提到了地球上最后一个冰河时期开始的时候,地球上发生了极不寻常的事,第2句则进行了解释。从第2句的句子结构来看,只要找出句子的主语和谓语,将中间的定语从句和插入部分省去,即可发现剩下的内容是Sea levels...suddenly rose,这就是最后一个冰河时期开始时发生的事,可见本题应选C。
转载请注明原文地址:https://tihaiku.com/zcyy/2925986.html
相关试题推荐
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
Thathealthandbeautyarelinkedisnotindoubt.Butitcomesassomething
[originaltext]Newscanbesomethingtheauthoritieswantyoutoknow,orso
[originaltext]W:Hello,Tom,couldyoupleasetellmesomethingaboutdrivingl
随机试题
1InproposedchangestoTitleIX,thefederallawprohibitingsexdiscri
论述实行跨国并购的优缺点。
图示体系是()。 A.几何不变体系,无多余约束 B.瞬变体系 C.几何不
阅读下列说明和C代码,回答问题1和问题2,将解答填入答题纸的对应栏内。
C所有图形都是一笔画图形。故答案为C。
Thechangeinthatvillagewasmiraculou
Internet主要由四大部分组成,其中包括路由器、主机、信息资源与: A.数
兴华房地产开发公司承揽开发一普通住宅项目,该项目预计投资3000万元,其现金流量
下列占用耕地的情形中,减按每平方米2元的税额征收耕地占用税的有( )。A.
劳动合同履行过程中,劳动者不需事先告知用人单位,可以立即与用人单位解除劳动合同的
最新回复
(
0
)