首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional
admin
2018-06-06
48
问题
No very satisfactory account of the mechanism that caused the formation of the ocean basins has yet been given. The traditional view supposes that the upper mantle of the earth behaves as a liquid when it is subjected to small forces for long periods and that differences in temperature under oceans and continents are sufficient to produce convection in the mantle of the earth with rising convection currents under the mid-ocean ridges and sinking currents under the continent. Theoretically, this convection would carry the continental plates along as though they were on a conveyer belt and would provide the forces needed to produce the split that occurs along the ridge.
This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. On the other hand, the theory is implausible because convection does not normally occur along lines, and it certainly does not occur along lines broken by frequent offsets or changes in direction, as the ridge is.
It has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving plate has an impact on the forces that move it, could produce complicated and varying motions.
Also it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. It would be odd if the rising convection currents kept exact pace with them.
An alternative theory is that the sinking part of the plate, which is denser than the hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part.
Another possibility is that the sinking plate cools the neighboring mantle and produces convection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of span. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods.
These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods. It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth’s surface and seriously require explanation because, in addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea.
Which of the following, if it could be demonstrated, would most support the traditional view of ocean formation?
选项
A、Convection usually occurs along lines.
B、The upper mantle behaves as a dense solid.
C、Sedimentation occurs at a constant rate.
D、Sinking plates cool the mantle.
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/02SO777K
本试题收录于:
NAETI中级口译笔试题库外语翻译证书(NAETI)分类
0
NAETI中级口译笔试
外语翻译证书(NAETI)
相关试题推荐
InDecember,WaymoLLC,theleadingdriverlesscarcompany,broughtouttheworld’sfirstcommercialrobo-taxiservice.Butfor
DemonstratorsrallyatLosAngelesCityHallduringthefirstWomen’sMarch,heldonJan.21,2017,onedayafterPresidentTrum
ThinkTwice:It’sAllRightAlegendaryfigureinmusichistory,Dylan,bornin1941,is【C1】______oneofthemostinfluentia
AtarecentdebateinWashingtonabouttheriseofChina,aU.S.careerdiplomatstruckanoptimisticnote.Yes,Chinawouldpro
AtatimewhenstandardsforITandartificialintelligenceriskbysplittingintoaChinesecampandanAmericanone,Europeca
Thiscountryisinthesocialtransformationperiodnow,andthesocialtransformationis______tobringdeepchangesoffemale
首先,我感谢莱文校长的邀请,使我有机会来到世界著名学府耶鲁大学,同青年朋友和老师们相聚在一起。进入耶鲁大学的校园,看到莘莘学子青春洋溢的脸庞,呼吸着书香浓郁的空气,我不由回想起40年前在北京清华大学的求学岁月。当年老师们对我的教诲,同学们给我的启发,我至今
儿童的生存、保护和发展是提高人口素质的基础,直接关系到一个国家和民族的前途与命运。中华民族素有“携幼”、“爱幼”的传统美德,中国古语“幼吾幼以及人之幼”流传至今。中国政府一向以认真和负责的态度,高度关心和重视儿童的生存、保护和发展,把“提高全民族
A、dyslexiaandintelligenceB、dyslexiaandcultureC、dyslexiaandvisionD、dyslexiaandpersonalityB将主题句中的关键词与选项中的关键词对比,可找出正确答案
A、Noonehasprovidedanaccuratedescriptionoftheanimal.B、Nodeadbodiesoftheanimalhaveeverbeenfound.C、Thereareon
随机试题
下列选项中,关于组织培训与开发决策分析的说法,错误的是()。
婴儿所需的适宜室温和病室相对湿度是【】
下列选项中,属于专业监理工程师的职责的有( )。
强度大、不易变形、密封性能较好的法兰为()。
战略制定是指根据外部环境、自身条件,从不同的总体战略和业务战略中选择适宜的战略。下列说法中,不正确的是()。
下列项目中,不符合消费税纳税义务发生时间规定的有()。
设X~N(μ,σ2),σ未知,xi为样本(i=1,2,…,n)。H0:μ≤μ0,H1:μ>μ0,α为显著性水平,则接受域()。
子网掩码为255.255.255.0代表()。
LakeTrummeninsouthernSwedenusedtobeapolluted,weed-chokedmess.Now,aftera$14millioncleanup,batherscrowditscle
Almosteverynewinnovationgoesthroughtherephases.Wheninitiallyintroducingintothemarket,theprocessofadoptionissl
最新回复
(
0
)