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
Volcanic fire and glacial ice are natural enemies. Eruptions at glaciated volcanoes typically destroy ice fields, as they did in
Volcanic fire and glacial ice are natural enemies. Eruptions at glaciated volcanoes typically destroy ice fields, as they did in
admin
2012-03-21
24
问题
Volcanic fire and glacial ice are natural enemies. Eruptions at glaciated volcanoes typically destroy ice fields, as they did in 1980 when 70 of Mount Saint Helens ice cover was demolished. During long dormant intervals, glaciers gain the upper hand cutting deeply into volcanic cones and eventually reducing them to rubble. Only rarely do these competing forces of heat and cold operate in perfect balance to create a phenomenon such as the steam caves at Mount Rainier National Park.
Located inside Rainier’s two ice filled summit craters, these caves form a labyrinth of tunnels and vaulted chambers about one and one half miles in total length. Their creation depends on an unusual combination of factors that nature almost never brings together in one place. The cave making recipe calls for a steady emission of volcanic gas and heat, a heavy annual snowfall at an elevation high enough to keep it from melting during the summer, and a bowl shaped crater to hold the snow.
Snow accumulating yearly in Rainier’s summit craters is compacted and compressed into a dense form of ice called firm, a substance midway between ordinary ice and the denser crystalline ice that makes up glaciers. Heat rising from numerous openings (called fumaroles) along the inner crater walls melts out chambers between the rocky walls and the overlying ice pack. Circulating currents of warm air then melt additional openings in the firm ice, eventually connecting the individual chambers and, in the larger of Rainier’s the crater’s, forming a continuous passageway the extends two thirds of the Way around the crater’s interior.
To maintain the cave system, the elements of fire under ice must remain in equilibrium, enough snow must fill the crater each year to replace that melted from below. If too much volcanic heat is discharged, the crater’s ice pack will melt away entirely and the caves will vanish along with the snows of yesteryear. If too little heat is produced, the ice, replenished annually by winter snowstorms, will expand, pushing against the enclosing crater walls and smothering the present caverns in solid firm ice.
With what topic is’ the passage mainly concerned?
选项
A、The importance of snowfall for Mount Rainier.
B、The steam caves of Mount Rainier’s.
C、How ice covers are destroyed.
D、The eruption of Mount Saint Helens in 1980.
答案
B
解析
大意判断题。文章说明了the steam caves of Mount Rainier形成的特殊情况与天气、地理条件,这是文章的主旨所在。
转载请注明原文地址:https://kaotiyun.com/show/rsmK777K
0
专业英语四级
相关试题推荐
Thelocalgovernmenthasto______thetaxschemebecauseofthestrongopposition.
WhatisIsraelprobablytodoifPalestiniansattackitssoldiersduringthepullout?
Unlikemostsports,whichevolvedovertimefromstreetgames,basketballwasdesignedbyonemantosuita【C1】______purpose.
Unlikemostsports,whichevolvedovertimefromstreetgames,basketballwasdesignedbyonemantosuita【C1】______purpose.
Themessageisclear:Justasteaandbananacant’tgotogether,______shouldthesonofalow-classfamilyexpecttomarrythe
TheEisteddfodisafestival______entirelytomusicandliteratureintheWelshLanguageandheldforweekinAugustinWales.
Jealousytypicallyreferstothethoughts,feelings,andbehaviorsthatoccurwhenapersonbelievesavaluedrelationshipisbe
Jealousytypicallyreferstothethoughts,feelings,andbehaviorsthatoccurwhenapersonbelievesavaluedrelationshipisbe
Whywouldanyonewanttosetasideadaytohonoralowlylittlegroundhog?Theanswertothatquestionisnotcertain,butagr
Theboarddeemediturgentthatthesefiles_____rightaway.
随机试题
除法律、行政法规另有规定的除外,公司的注册资本和实收资本应当以__________表示。
胼胝体发育不良的CT征象包括
The purpose( )my coming here is to inquire about possibilities of establishing trade relations with your company.
甲公司20×9年度发生的有关交易或事项如下:(1)20×9年6月l0日,甲公司所持有子公司(乙公司)全部80%股权,所得价款为4000万元。甲公司所持有乙公司80%股权系20×6年5月10日从其母公司(己公司)购入,实际支付价款2300万元,合并日乙公
群体的主要功能有【】
【2015年河南邓州.判断】儿童希望与小伙伴建立友谊,希望得到教师和父母的爱,反映了儿童归属感和爱的需要。()
社会工作是一种()。
领导临时有事无法参加会议,他让科长去参加会议并做一个报告,但这次报告的工作内容并不属于科长工作范围。假如你是这名科长。你会怎么办?
从四个图中选出唯一的一项,填入问号处,使其呈现一定的规律性。
求极限
最新回复
(
0
)