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
62
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://www.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
WalkbyanyStarbuckswithinseveralmilesofyourhouse,thechancesarethatyou’llseeseveralpeoplesittingatatable,dri
MaintainingFriendshipinAdolescenceSecondaryschoolcanbea【C1】______placeforadolescentswhodon’thaveabestfriend
Consumers______thecompetitiveresultofyourspecialopponentbutnotyourproduct,becauseitishardtoknowyourproduct’sq
AtarecentdebateinWashingtonabouttheriseofChina,aU.S.careerdiplomatstruckanoptimisticnote.Yes,Chinawouldpro
Asthefederalgovernmentshutdownapproachesthetwo-weekmark,it’sbecomepainfullyapparentthatthepubliccannolongerru
VisitorstoBritainmayfindthebestplacetosamplelocalcultureisinatraditionalpub.Butthesefriendlyhostelriescanb
Hewaslookingimpatientatthevisitingsalesman,whoshowednosignsofgettingreadytoleave.
加强区域能源合作共创亚太美好未来资源节约与综合利用司副司长 刘显法2002年7月25日各位来宾、女士们、先生们:上午好!今天,我们在这里
人类有史以来,迷信就是人们生活中的一部分。即使在如今的科技时代,大多数人哪怕表面上装作不迷信,也会在背地里迷信某些事物。
A、IwonderedifJoehasfinishedhisresearch.B、I’minterestedinhisadvisor’sprojections.C、IthinkJoeshouldhavetalkedt
随机试题
气门密封性试验常见方法有_______、_______、_______。
简述计划工作的基本特征。
患者张××,女性,22岁,农民。G2P0A1L0。因“停经35+6周,规律性下腹痛3小时”入院。患者自诉有先天性心脏病(法洛四联症)病史,未行手术矫正。孕期生活可自理。近一周轻微活动后即感不适,休息后可缓解。夜间可平卧。查体:T36.6℃,P90次/分
下面的组织脱水剂是乙醇的良好替代品的是
患者,女,44岁。月经紊乱一年多,阵发性潮热,腰膝酸软,头晕耳鸣。针灸时以
液压传动系统中节流阀通过改变()来控制流量的大小。
信用公司债券是一种不以公司任何资产作担保而发行的债券,属于无担保证券范畴。()
女职工甲与某公司依法签订无固定期限劳动合同。2017年7月,甲怀孕,由于年龄较大,需要保胎,甲多次迟到或者不上班。2018年7月至12月累积15天没有上班。某公司规章规定,累计旷工10天以上构成严重违反用人单位规章。据此,公司与甲解除了劳动合同。甲认为公司
人生观与世界观有着密切的关系。一个人思考生活的意义,确立对待生活的方式总会受到他所具有的世界观的影响。人生观和世界观的关系是
Argentina(landofsilver)wasgivenitsnameby16th-centuryexplorerswhobelievedthecountrywasrichinsilvermines.Thehop
最新回复
(
0
)