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
考研
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
2008-12-26
84
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 mil lion 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 deed 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).
选项
A、the motion of the plates corresponds to that of the earth’s interior
B、the geological theory about drifting plates has been proved to be truse
C、the hot spots and the plates move slowly in opposite directions
D、the movement of hot spots proves the continents are moving apart
答案
B
解析
短文第二段段首句告诉我们:对于板块漂移这一理论现已无人质疑,及随后列举的有关非洲及南美洲板块的实例,我们可以判断选项"关于板块漂移这一理论现已被证实是正确的"为正确答案。
转载请注明原文地址:https://www.kaotiyun.com/show/7ui4777K
0
考研英语一
相关试题推荐
设函数y=f(x)由方程y3+xy2+x2y+6=0所确定,求f(x)的极值.
设连续型随机变量X1与X2相互独立,且方差均存在,X1与X2的概率密度分别为f1(x)与f2(x),随机变量Y1的概率密度为,随机变量Y2=,则().
Excitement,fatigue,andanxietycanallbedetectedfromsomeone’sblinks,accordingtopsychologistJohnStern(21)Washington
Theconference______thepossibilityofestablishingcloserdiplomaticrelationshipbetweenthetwocountries.
Nameshavegainedincreasingimportanceinthecompetitiveworldofhighereducation.Ascollegesstriveformarketshare,they
Theeldestson______allthefamilymemberstodiscusshowtocelebratethe50thweddinganniversaryoftheirparents.
Itseemstohappenwithdepressingfrequency—sunnyskiesturntorainjustastheweekendarrives.NowSpanishresearcherssayt
IfIaskyouwhatconstitutes"bad"eating,thekindthatleadstoobesityandavarietyofconnecteddiseases,you’relikelyto
[A]financialaidshouldbeprovidedtopoorcountriesthatarewithawidevarietyofplantsandanimals.[B]everyonewillsin
随机试题
男,23岁,右大腿下端持续性隐痛1个月余。查体:右大腿下端内侧肿胀,压痛。X线摄片见右股骨下端偏内侧有一骨破坏区,呈肥皂泡样膨胀性生长;病灶局限,类圆形,骨皮质变薄。应首先考虑的疾病为
张某,男性,30岁,电工。Ⅲ度烧伤,烧伤总面积70%,对该患者采用
开标时,招标人对()都应当当众予以拆封、宣读。
开办银团贷款业务的银行应当定期向当地银行业协会报送银团贷款有关信息,其内容主要有()。
家庭衰老期的投资组合中现金比重应该最高。()
薛某大学毕业后,实际工作年限为5年,2012年10月1日在某上市公司工作已满2年,还有1年的合同期。如果从2012年10月25日起第一次病休,则薛某享受医疗期的时间段应是()。
下列属于形容天气的诗句是:
一个人在选择读博士还是参加工作的时候,面临着:如果读博士,就不能工作,如果不工作,生活就拮据。由此可推出()。
Whataspectofantsdoesthepassagemainlydiscuss?Theword"alert"inline13isclosestinmeaningto
Whatisthewomantryingtodo?
最新回复
(
0
)