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
In Death Valley, California, one of the hottest, most arid places in North America, there is much salt, and salt can damage rock
In Death Valley, California, one of the hottest, most arid places in North America, there is much salt, and salt can damage rock
admin
2014-01-13
40
问题
In Death Valley, California, one of the hottest, most arid places in North America, there is much salt, and salt can damage rocks impressively. Inhabitants of areas elsewhere, where streets and highways are salted to control ice, are familiar with the resulting rust and deterioration on cars. That attests to the chemically corrosive nature of salt, but it is not the way salt destroys rocks. Salt breaks rocks apart principally by a process called crystal prying and wedging. This happens not by soaking the rocks in salt water, but by moistening their bottoms with salt water. Such conditions exist in many areas along the eastern edge of central Death Valley. There, salty water rises from the groundwater table by capillary action through tiny spaces in sediment until it reaches the surface.
Most stones have capillary passages that suck salt water from the wet ground. Death Valley provides an ultra-dry atmosphere and high daily temperatures, which promote evaporation and the formation of salt crystals along the cracks or other opening within stones. These crystals grow as long as salt water is available. Like tree roots breaking up a sidewalk, the growing crystals exert pressure on the rock and eventually pry the rock apart along planes of weakness, such as banding in metamorphic rocks, bedding in sedimentary rocks, or preexisting or incipient fractions, and along boundaries between individual mineral crystals or grains. Besides crystal growth, the expansion of halite crystals(the same as everyday table salt)by heating and of sulfates and similar salts by hydration can contribute additional stresses. A rock durable enough to have withstood natural conditions for a very long time in other areas could probably be shattered into small pieces by salt weathering within a few generations.
The dominant salt in Death Valley is halite, or sodium chloride, but other salts, mostly carbonates and sulfates, also cause prying and wedging, as does ordinary ice. Weathering by a variety of salts, though often subtle, is a worldwide phenomenon. Not restricted to arid regions, intense salt weathering occurs mostly in salt-rich places like the seashore, near the large saline lakes in the Dry Valleys of Antarctica, and in desert sections of Australia, New Zealand, and central Asia.
In lines 13-17, why does the author compare tree roots with growing salt crystals?
选项
A、They both force hard surfaces to crack.
B、They both grow as long as water is available.
C、They both reach quickly to a rise in temperature.
D、They both cause salty water to rise from the groundwater table.
答案
A
解析
根据文章第二段第三、四句“These crystals grow as long as salt water is available.Like tree roots breaking up a sidewalk,the growing crystals exert pressure on the rock and eventuallypry the rock apart along planes of weakness.”可知,作者指出:只要有盐水,晶体就会成长。晶体成长与树根植根于人行道一样:晶体对岩石施加压力,沿着其薄弱的地方撬开。树根会对地面用劲而将地面裂开。据此判断,答案是A。
转载请注明原文地址:https://kaotiyun.com/show/YbQO777K
0
考博英语
相关试题推荐
InanefforttoalleviateAmerica’sincreasingdependenceonforeignoilandmitigatetheworsteffectsofthecurrentpowercri
MarciaSeligsoncallstheweddingdressthe"keymetaphor"intheelaborateefforttomaketheAmericanweddingan"idealizedde
Distanceeducationisenrollmentandstudywithaneducationalinstitutionthatprovideslessonmaterialspreparedinasequenti
Areyoualwayssureyouknowwhatpeoplemeanwhentheytrytodescribetheirfeelingstoyou?Weusebothwordsandgesturesto
Areyoualwayssureyouknowwhatpeoplemeanwhentheytrytodescribetheirfeelingstoyou?Weusebothwordsandgesturesto
Consumersandproducersobviouslymakedecisionsthatmoldtheeconomy,butthereisathirdmajor【61】toconsidertheroleofg
Insuchachanging,complexsocietyformerlysimplesolutionstoinformationalneedsbecomecomplicated.Manyoflife’sproblems
Overthepasttwodecades,teenagechildbearingintheUnitedStates—asmeasuredbythenumberofbirthstoteenagers—hasdecrea
Itistruethatasasocialorganizationmovesfromthesimpletothecomplex,sodoestheorganizationthroughwhichiteducate
Thefirstsentenceinthisparagraphis______;itcanbeinterpretedinmanyways.
随机试题
Cursive(草书),theartofpenmanshipcastasideinrecentyearsasschoolsincreasinglyfocusonkeyboarding,maybegettingase
患者,男,65岁。近一个月经常眩晕,胸闷,乏力,痰多,心情不舒,昨日突然跌倒,神志不清,抽搐吐涎,舌质红,苔白腻,治疗宜选()
A.4天B.5~6天C.7~9天D.10~12天E.14天【2004年考试真题】
职业接触限值为最高容许浓度的有害物质,采用定点的采样方法,采样时间为()min。
深圳证券交易所会员取得席位后,只能申请设立1个交易单元。()
现场检查的分析技术方法包括()。
对个体发展起主导作用的是()。
A、 B、 C、 D、 C
MallaryWassurprisedbecausehe______.HowdidtheyoungMantreathisMother?
A、Theshapeofdifferentkindsoftea.B、Thetemperatureofmakingtea.C、Thedifferentplacesoftea.D、Theroastingandfermen
最新回复
(
0
)