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
2023-08-27
23
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/2963132.html
相关试题推荐
[originaltext]M:I’mgoingouttopickupahamburger.CanIgetyousomething?
[originaltext]M:I’mgoingouttopickupahamburger.CanIgetyousomething?
DoSomethingYou’veprobablyheardthecommonre
DoSomethingYou’veprobablyheardthecommonre
DoSomethingYou’veprobablyheardthecommonre
DoSomethingYou’veprobablyheardthecommonre
DoSomethingYou’veprobablyheardthecommonre
DoSomethingYou’veprobablyheardthecommonre
DoSomethingYou’veprobablyheardthecommonre
WehavetheevidencethatAppleisontosomething______(38家苹果店在建,还有更多店在筹建).with
随机试题
Receivingvisitorsandguestsisanimportantpartofthesecretary’sdaily
Peoplebecomequiteillogicalwhentheytrytodecidewhatcanbeeatenand
坚持不懈取决于三个方面——目标、意志和热情。有目标的人总能集中他的力量。凭借坚定的意志,就能使希望和计划不致化为梦幻,而是日有所进,积沙成塔。冲天的热情
甲亢初始治疗的首选方法是A.放射性碘治疗 B.替代治疗 C.抗甲状腺药物治疗
女性,45岁,风湿病史多年,近年来呼吸困难进行性加重,并出现颈静脉怒张,肝脏肿大
与喜食过硬、过热食物,进食过快、龋齿、口腔不洁,慢性刺激或炎症有关的疾病是A.胃
药物稳定与否的根本原因在于自身的化学结构,外界因素则是引起变化的条件,影响药物制
2013—2020年,全国普通高校毕业生人数同比增速超过4%的年份有几个
以应用知识为基础的薪酬是( )。A.岗位薪酬 B.绩效薪酬 C.技术薪酬
(2015年真题)环戊噻嗪、氢氯噻嗪、呋塞米、氯噻嗪的效价强度和效能见下图,对这
最新回复
(
0
)