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
2023-08-14
68
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 now beyond dispute. Africa and South America, for example, are moving away from each 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 comes to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops deep 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 (inconstancy). [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
关于hot spot theory的作用,除了第2段提到的参照作用外,第3段论及的另一个重要作用在于它能够推动板块在地球表面漂移(propel the plates across the globe),从而引发了新海洋的形成(initiates the formation of a new ocean)。故答案选D项。
转载请注明原文地址:https://tihaiku.com/zcyy/2924168.html
相关试题推荐
Theideaofusingyourdishwashertocookamealhasbeenaroundsincethe’
Theideaofusingyourdishwashertocookamealhasbeenaroundsincethe’
Theideaofusingyourdishwashertocookamealhasbeenaroundsincethe’
Theideaofusingyourdishwashertocookamealhasbeenaroundsincethe’
Manycountrieshaveaholidaytocelebrateworkers’rightsonoraroundMay
Manycountrieshaveaholidaytocelebrateworkers’rightsonoraroundMay
Manycountrieshaveaholidaytocelebrateworkers’rightsonoraroundMay
Manycountrieshaveaholidaytocelebrateworkers’rightsonoraroundMay
Manycountrieshaveaholidaytocelebrateworkers’rightsonoraroundMay
Manycountrieshaveaholidaytocelebrateworkers’rightsonoraroundMay
随机试题
Idon’tunderstandwhypeople______suchabeautifulgardenwithcansandbott
Peopleliveingroups,whichwecallsocieties,andsocialrelationsarethe
肝素的主要作用有()A.增强抗凝血酶与凝血酶的亲和力 B.加快灭活凝血酶的
据统计,目前我国老年人已达2.3亿,老年消费者这轮“夕阳”本应该成为推动GDP发
下列关于低行权价的期权说法有误的有( )。A.低行权价的期权的投资类似于期货的
注射用奥沙利铂的溶媒选择要求是A.氯化钠注射液稀释B.5%葡萄糖注射液稀释C
根据销售百分比法预测资金需要量时,下列项目中,通常会随销售额变动而呈正比例变动的
现代农业发展的( )是农业现代化的直接价值取向。A.技术目标 B.经济目标
下列有关审计证据的相关性的说法中,错误的是( )A.审计证据的相关性影响审计证
A.恙虫病 B.败血症 C.钩端螺旋体病 D.登革热 E.流行性出血热腓
最新回复
(
0
)