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
Volcanoes Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have n
Volcanoes Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have n
admin
2010-02-17
38
问题
Volcanoes
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 out heat all the time as the heat inside the earth is produced by radioactive elements.
Whatever the cause of the heat may be, we do know that the earth gets hotter the farther down we dig. In deep mines and oil wells the temperature rises about 1’F. for each 50 feet. At this rate the temperature 40 miles below the earth’s surface would be over 4,000’F. This is much hotter than necessary to melt rock. However, the pressure of the rock above keeps most materials from melting at their usual melting points. Geologists believe that the rock deep in the earth may be plastic, or puttylike. In other words, the rock yields slowly to pressure but is not liquid. But if some change in the earth’s crust releases 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’s crust, a volcano may be formed. The melted rock often contains steam and other gases under great pressure. If the rock above 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 the 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.
If the temperature at the earth’s surface is twenty degrees Fahrenheit, the temperature in a coal mine 500 feet below the surface would, in degrees, be ______.
选项
A、50
B、40
C、30
D、120
答案
C
解析
参见第二段第一、二句。500英尺的垂直落差会带来10度的温差。
转载请注明原文地址:https://kaotiyun.com/show/rtnK777K
0
专业英语四级
相关试题推荐
A、Laws.B、Opinions.C、Etiquette.D、Fashion.B细节题。关于社会规范,受访者提到:Socialnorms,therefore,arethepartofculturelearnedbyallmemb
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
PassageThreeWhatattributeaboutDenimcanbelearnedfromthemanyUSPresidents’wearingofjeans?
PassageTwo(1)It’sagoldenageforstudyinginequality.ThomasPiketty,aFrencheconomist,setthebenchmarkin2014wh
随机试题
简述根据我国《土地管理法》的规定,由国务院批准征收土地的情况。
Afteralong______thebillwaspassedbythepeople’scongress.
药物不良反应有多种诱发因素,其发生频率和严重程度与这些因素紧密相关,格列美脲引起的低血糖反应属于
乙脑传染源主要是霍乱传染源是
个人汽车贷款以商品住房抵押的,比率不得超过()。
客户开户时,理财师可以协助客户填写一份类似《客户信息采集表》,内容可包括()。
2014年7月1日,某企业向银行借入500万元的借款,期限3个月,到期一次还本付息,年利率为3%,借款利息按月预提,2014年9月30日该短期借款的账面价值为()万元。
癌基因表达产物具有
运动会中一个运动项目可以有多名运动员参加,一个运动员可以参加多个项目。则实体项目和运动员之间的联系是
Lightisdifferent______sound______thewayittravels.
最新回复
(
0
)