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
2019-06-23
59
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).
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://kaotiyun.com/show/nJX7777K
0
大学英语六级
相关试题推荐
A、All-arounddevelopmentB、Creativityforthefuture.C、Basicsocialskills.D、Academiccapability.D演讲者提到现在我们的教育体制建立在学术能力的概念上,学
A、Lessthan68%.B、About50%.C、Over70%.D、Around45%.C短文从一开头就提到,食品生产商很关注食品标签上的内容,因为有超过于70%的消费者购买食品前会读食品上的标签。
A、SleepinginanopenenvironmentB、Usingfuelinsteadofelectricity.C、Usingsmallandmovablegasgenerators.D、Short-termco
A、Mealsareprovidedfreeofcharge.B、Studentsaremoresecure.C、Studentsneedn’tdevotetimetohousekeeping.D、Studentshave
ThebesttimetoviewtheMonaLisa,accordingtoanewbookonthebesttimestodothings,isaroundnineo’clockonaSunday
ThebesttimetoviewtheMonaLisa,accordingtoanewbookonthebesttimestodothings,isaroundnineo’clockonaSunday
ThebesttimetoviewtheMonaLisa,accordingtoanewbookonthebesttimestodothings,isaroundnineo’clockonaSunday
A、Above50%.B、About25%.C、Around68%.D、Approximately94%.B
Theconceptofobtainingfreshwaterfromicebergsthataretowedtopopulatedareasandaridregionsoftheworldwasoncetrea
随机试题
关于痛经,错误的是
关于不作为犯,下列哪些选项是正确的?
在计算机系统中,设备管理是指对()。
图5—6—7所示圆轴,在自由端圆周边界承受竖直向下的集中力F,按第三强度理论,危险截面的相当应力σeq3为()。[2009年真题]
公安机关是政府的一个职能部门,但又不同于一般行政机关;人民警察是国家公务人员,但又不同于政府其他部门的公务员。因此,对人民警察的素质和职业道德必须有更高更专业的要求。()
对下列危害道路交通安全行为的处罚,符合相关法律规定的是:
Nor,ifconformitytoastandardpatternisasdesirabletothescientistasthewritingofhispaperswouldappeartoreflect,
Musicmeansdifferentthingstodifferentpeopleandsometimesevendifferentthingstothesamepersonatdifferentmomentsof
数据字典是各类数据描述的集合,它通常包括5个部分,即数据项、数据结构、数据流、______和处理过程。
Larrymadeademandthatthesuspect______intheman’sroomthatnight.
最新回复
(
0
)