首页
登录
职称英语
Scattered around the globe are more than 100 small regions of isolated volca
Scattered around the globe are more than 100 small regions of isolated volca
游客
2025-04-07
9
管理
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). [br] 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://tihaiku.com/zcyy/4030293.html
相关试题推荐
TheAmericaneconomicsystemisorganizedaroundabasicallyprivate-enterpr
TheAmericaneconomicsystemisorganizedaroundabasicallyprivate-enterpr
Aroundtheworldmoreandmorepeoplearetakingpartindangeroussportsan
Scatteredaroundtheglobearemorethan100smallregionsofisolatedvolca
Scatteredaroundtheglobearemorethan100smallregionsofisolatedvolca
Scatteredaroundtheglobearemorethan100smallregionsofisolatedvolca
Thegovernment-runcommandpostinTunisisstaffedaroundtheclockbymili
Thegovernment-runcommandpostinTunisisstaffedaroundtheclockbymili
Thegovernment-runcommandpostinTunisisstaffedaroundtheclockbymili
______therewasnotasoularoundexceptsomecarspassingoccasionally.A、Overn
随机试题
[originaltext]TodayI’dliketotalkaboutthesculptorHenryMoore,inpar
[originaltext]W:I’mallpacked.(22)Take-offtimeis2:30a.m.thedayaftert
甲公司只生产一种产品,变动成本率为40%,保本作业率为70%。甲公司的销售利润率
某时期内,某国粮食价格持续下跌。为了保护农民的利益,该国政府因此规定了粮食最低收
下列有关全业使命和愿景的表述,不正确的量()A.企业愿景是比较长期和抽象的 B
#_2是理解科学知识的起点,是学生由不知到知的开端,是知识获得的首要环节。
(2020年真题)根据消费税法律制度的规定,下列应税消费品中,实行从量计征办法计
在确定控制措施或考虑改变现行控制措施时考虑按()顺序选择风险控制方法。A.替代
公路路面工程专业承包企业资质可一共分为()。A.二级 B.三级 C.四级
根据《建设工程安全生产管理条例》,施工单位应当组织专家对施工方案进行论证、审查的
最新回复
(
0
)