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
33
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
WhichofthefollowingisregardedasAmerica’s"DeclarationofIntellectualInd
[originaltext]Theeconomiccostsofnoisetosocietyareseveral.Airports
计算居住小区室外给水管道设计流量时,下列哪种因素不必考虑?( )A.服务人数
患者,男性,46岁,一天来乏力,头晕,面色苍白,上腹部疼痛,恶心,出冷汗,无腹泻
膀胱癌最主要的症状是()A.排尿困难 B.膀胱刺激征 C.无痛性肉眼血
产后“三病”指的是A.惊厥、眩晕、泄泻 B.郁冒、惊厥、大便难 C.发热、郁
上消化道出血最常见的原因是()A.慢性胃炎 B.食管胃底静脉曲张 C.胃癌
收益法的本质是以房地产的()为导向求取估价对象的价值。A、预期未来收益 B
糖酵解的关键酶有 A.6磷酸果糖激酶1B.丙酮酸脱氢酶复合体 C.丙酮酸
下列关于销售物流成本管理的原则,说法错误的是()。A.从流通全过程角度,要考虑
最新回复
(
0
)