首页
登录
职称英语
Geologists have been studying volcanoes for a long time. Though they have l
Geologists have been studying volcanoes for a long time. Though they have l
游客
2024-10-31
20
管理
问题
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered the causes of volcanic action. They know that the inside of the earth is very hot, but they are not sure exactly what causes the great heat. Some geologists have thought that the heat is caused by the great pressure of the earth’s outer layers. Or the heat may be left from the time when the earth was formed. During the last sixty years scientists have learned about radium, uranium, thorium and other radioactive elements. These give ont heat all the time as they change into other elements. Many scientists now believe that much of the heat inside the earth is produced by radioactive element.
Whatever the cause of the heat may be, we do know that the earth get hotter the farther down we dig. In deep mines and oil wells the temperature rises about 1 for each 50 feet. At this rate the temperature 40 miles below the earth’s surface would be over 4,0007 This is much hotter than necessary to melt rock. However, the pressure of the reek above keeps most materials from melting at their usual melting points. Geologists believe that the rock deep in the earth may be plastic, or putty-like. In other words, the rock yields slowly to pressure but is not liquid. But if some change in the earth’s crust re leases the pressure, the rock melts. Then the hot, liquid rock can move up toward the surface.
When the melted rock works its way close to the earth crust, a volcano may be formed. The melted rock often contains steam and other gases under great pressure. If the rock above often gives way, the pressure is released. Then the sudden expansion of the gases causes explosions. These blow the melted rock into pieces of different sizes and shoot them high in the air. Here they cool and harden into volcanic ash and cinders. Some of this material falls around the hole made in the earth’s surface. The melted rock may keep on rising and pour out as lava. In this way, volcanic ash, cinders and lava build up the cone-shaped mountains that we call volcanoes. [br] The cause for the heat in the interior of the earth is ______.
选项
A、radioactive element
B、the great pressure of the earth
C、not determined
D、volcanic action in the interior of the earth
答案
C
解析
根据第一段第三句,我们知道,对高温的成因有几种观点,但人们认识并不完全一致。因此,选C,而排除其他各项。
转载请注明原文地址:https://tihaiku.com/zcyy/3825628.html
相关试题推荐
Thoughshedidnotwishforamedicalprofession.Miriamdidnotsayanythingan
Iwon’tgiveyouanaccountofallmywanderings,thoughIhavebeenmostindefa
Although________inareligiousfamily,hedidnotbelieveinGodatall.A、grown
Hepolitelyrefrainedhimself______sayingwhathethoughtofherhat.A、against
AlthoughAnneishappywithhersuccessshewonders______willhappentoherpr
VolcanoesGeologistshavebeenstudyingvolcano
Althoughhethoughthewashelpingustopreparethedinner,hewasactually____
Thoughjanewasoffendedbyhersister’sruderemarks,sheonly______herlips
______I’dliketo,Ican’tcome.A、MuchthoughB、ThoughmuchC、MuchasD、Asmuch
Althoughmanypeopleviewconflictasbad,conflictissometimesuseful______i
随机试题
(1)SocialmobilityintheU.K.couldbereversedunlessthegovernmentandu
WhowontheWorldCup1998footballgame?WhathappenedattheUnitedNation
Videorecordersandphotocopiers,eventicketmachinesontherailways,ofte
[originaltext]M:SowhatdoesacharteredsurveyordoinEssex?Canyoutellus
2016年12月14日财政部发布了《管理会计实践索引(一)》
确诊阴道炎病原体的最好方法是A.悬滴法 B.PCR法 C.革兰氏染色法 D
瘟病后期阴虚邪伏者,治疗应首用的方剂是A.清骨散 B.清营汤 C.当归六黄汤
某流程图如下图所示,执行该算法,下列说法中错误的是()。 A.s的值最终为
初中生小强学习成绩一直不好,老师和家长都十分头痛,他变得自暴自弃,学校社会工作者
关于团体对个体从众行为影响的说法,错误的是()。A.团体凝聚力越大,个体越容
最新回复
(
0
)