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
2024-04-26
41
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 the glaciers were melting at a tremendous rate?
选项
A、The mid-latitudes were flooded first.
B、The climate lost its regular balance.
C、The ice age almost came to an end.
D、The sea level rose rather quickly.
答案
D
解析
第6段第1句开头的that指的是第5段提到的海平面以很快的速度上升这个事实,这两句话表明海平面上升和冰川融化有联系,因此,本题应选D。
转载请注明原文地址:https://tihaiku.com/zcyy/3571915.html
相关试题推荐
Somethingveryunusualhappenedabout80,000yearsago,asEarth’slastice
Somethingveryunusualhappenedabout80,000yearsago,asEarth’slastice
AremarkablethinghappenedinNewYorkrecently:thestatelegislature,in
AremarkablethinghappenedinNewYorkrecently:thestatelegislature,in
[originaltext]M:Maybeit’ssomethingIhavetomentionaboutIranians,wedon’
[originaltext]M:LookatthelowpricesonthesefashionableTVsets.Something
[originaltext]M:LookatthelowpricesonthesefashionableTVsets.Something
[originaltext]M:LookatthelowpricesonthesefashionableTVsets.Something
[originaltext]M:LookatthelowpricesonthesefashionableTVsets.Something
[originaltext]M:LookatthelowpricesonthesefashionableTVsets.Something
随机试题
Itwouldbeinterestingtodiscoverhowmanyyoungpeoplegotouniversityw
Therearetwofactorswhichdetermineanindividual’sintelligence.Thefirs
对主管人员工作成效的衡量,应该做到()。A.对其工作和个人素质同时进行考评
初生婴儿的胎粪特点是()A.卵黄色,稠而不成形 B.大便稀薄,色黄秽臭
聚酰胺的吸附原理是A.相似者易于吸附B.相似者难于吸附C.氢键吸附D.离子交换吸
如图,利用小角法测定观测点P与基准线AB间的水平位移Δ,已知P点距A点的距离S为
下面关于卡马西平的特点,不正确的是A:对失神性发作首选 B:作用机制与抑制Na
从所给的四个选项中,选择最合适的一个填入问号处,使之呈现一定的规律性:
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
下列不属于车辆购置税的纳税人是()A.在我国境内购置应税车辆自用的行政事业单位
最新回复
(
0
)