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
Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlik
Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlik
admin
2017-07-31
87
问题
Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world’s volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth’s surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.
That the plates are moving is not beyond dispute. Africa and South America, for example, are moving away from eath other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth’s interior. It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it. Hot spots, anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the question. From an analysis of the hot spot population it appears that the African plate is stationary and that it has not moved during the past 30 million years.
The significance of hot spots is not confined to their role as a frame of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate come to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops seed fissures(cracks); in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus just as earlier theories have explained the mobility of the continents, so hot spots may explain their mutability(inconstant).
The hot spot theory may prove useful in explaining______.
选项
A、the structure of the African plates
B、the revival of dead volcanoes
C、the mobility of the continents
D、the formation of new oceans
答案
D
解析
本题可参照文章的第3段。从中可知,热点区的重要性并不仅在于它们所起到的参照物作用;现在看来,它们还对推动板块在地球上移动的地球物理学的过程也产生了重大影响;当大陆板块漂移到热点区上方时,地壳深处涌出的物质会形成一个巨大的穹顶;随着穹顶不断增长,它会出现深深的裂缝;如此作用几次后,大陆可能会沿着这些小裂缝完全裂开,这样热点地区就导致了新大洋的诞生。于是,该热点便开始形成一个新海洋;因此,正如早期的理论解释了大陆的移动那样,热点或许可以解释大陆的易变性。据此可知,热点理论可以用于解释大陆的不稳定性,即热点可以促使形成新海洋。D项与文章的意思相符,因此D项为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/eiFO777K
0
考博英语
相关试题推荐
Thenormalhumandailycycleofactivityisofsome7-8hours’sleepalternationwithsome16-17hours’wakefulnessandthatthe
HowtoDoFewer,BetterAnimalExperimentsForanationofpetlovers,Britainconductsasurprisingnumberofexperimentso
Atthefall2001SocialScienceHistoryAssociationconventioninChicago,theCrimeandJusticenetworksponsoredaforumonth
____aresearchstudent,Iwouldatleastmastertwoforeignlanguages.
Everyoneitseemshasahealthproblem.AfterpouringbillionsintotheNationalHealthService,Britishpeoplemoanaboutdirty
Opinionpollsarenowbeginningtoshowthat,whoeveristoblameandwhateverhappensfromnowno,highunemploymentisprobabl
Ihearmanyparentscomplainingthattheirteenagechildrenarerebelling.Iwishitwereso.Atyourageyououghttobegrowin
IworkasanofficeassistantinasmallbutgrowinggardenequipmentmanufacturingcompanyinCalifornia.Afewmonthsago,my
Largeanimalsthatinhabitthedeserthaveevolvedanumberofadaptationsforreducingtheeffectsofextremeheat.【C1】______ad
IthadbeenaterribleafternoonforJane,______ataboutsixo’clockinherfather’ssuddencollapseintounconsciousness.
随机试题
维持躯体姿势的最基本的反射是()
糖蛋白中的N-糖链的最主要生理功能是
患者,男,22岁。踢足球时向后跌倒,摔伤右肩部来诊。检查见右肩部方肩畸形,肩关节空虚,弹性固定,Dugas征阳性。若该患者合并骨折,最多见的是
B县人民法院受理王强诉周春海名誉侵权纠纷一案,判决周春海在判决生效后一个月内赔偿王强2万元,并在《A市日报》登报赔礼道歉。周春海不服,提起上诉。A市中级人民法院经审理作出二审判决,维持原判。判决送达后,周春海向王强交付了2万元的赔偿款,但未按期赔礼道歉。王
下列哪些情形是逃避迫缴欠税罪的要件?
如果某债券实际预期收益率约为6%,预期通货膨胀率约为4%,则该债券名义收益率约为()。
安全库存是由于批量订货而带来的库存。()
简述泰勒的课程设计模式。
走动管理,是指高阶主管经常抽空前往各个办公室走动,以获得更丰富、更直接韵员工工作问题,并及时了解所属员工工作困境的一种策略。根据上述定义,下列属于走动管理的是:
设f(x)在[a,+∞)上阶可导,且f(a)>0,f′(a)<0,又当x>a时,f′(x)<0,证明:有且仅有一个ξ∈(a,+∞),使f(ξ)=0.
最新回复
(
0
)