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
Rocks which have solidified directly from molten materials are called igneous rocks. Igneous rocks are commonly referred to as p
Rocks which have solidified directly from molten materials are called igneous rocks. Igneous rocks are commonly referred to as p
admin
2011-04-26
37
问题
Rocks which have solidified directly from molten materials are called igneous rocks. Igneous rocks are commonly referred to as primary rocks because they are the original source of material found in sedimentaries and metamorphics. Igneous rocks compose the greater part of the earth’s crust, but they are generally covered at the surface by a relatively thin layer of sedimentary or metamorphic rocks. Igneous rocks are distinguished by the following characteristics: (1) they contain no fossils; (2) they have no regular arrangement of layers; and (3) they are nearly always made up of crystals.
Sedimentary rocks are composed largely of minute fragments derived from the disintegration of existing rocks and in some instances from the remains of animals. As sediments are transported, individual fragments are assorted according to size. Distinct layers of such sediments as gravels, sand, and clay build up, as they are deposited by water and occasionally wind. These sediments vary in size with the material and the power of the eroding agent. Sedimentary materials are laid clown in layers called strata.
When sediments harden into sedimentary rocks, the names applied to them change to indicate the change in physical state. Thus, small stones and gravel cemented together are known as conglomerates; cemented sand becomes sandstone; and hardened clay becomes shale. In addition to these, other sedimentary rocks such as limestone frequently result from the deposition of dissolved material. The ingredient parts are normally precipitated by organic substances, such as shells of clams or hard skeletons of other marine life.
Both igneous and sedimentary rocks may be changed by pressure, heat, solution, or cementing action. When individual grains from existing rocks tend to deform and interlock, they are called metamorphic rocks. For example, granite, an igneous rock, may be metamorphosed into a gneiss or a schist. Limestone, a sedimentary rock, when subjected to heat and pressure may become marble, a metamorphic rock. Shale under pressure becomes slate.
In a granite quarry, we may expect to find ______.
选项
A、strata
B、limestone
C、metamorphic rock
D、no trace of fossils
答案
D
解析
在花岗岩矿中,我们也许找不到化石的遗迹。作者在最后一段指出,花岗岩属于火成岩;还在第一段指出,可以根据三个特征识别火成岩:第一,它们不包含化石;第二,它们的岩层排列不规则;第三,它们几乎总是由水晶构成的。
转载请注明原文地址:https://jikaoti.com/ti/c55YFFFM
0
考博英语
相关试题推荐
ReadthefollowingreviewsofabookcalledTheBossesSpeak.Foreachquestion23-28,choosethecorrectanswer.Markl
MrRansoncalledwhileyouwereonthephone-he’lltryagainthisafternoon.MrRanson______.
Imtexcalled—theirorderisn’tdueuntilnextmonth,butthey’dliketopicksamplesupearlierifpossible.Imtexwantsto
ReadthefollowingreviewsofabookcalledTheBossesSpeak.Foreachquestion23-28,choosethecorrectanswer.Markletter
ReadthefollowingreviewsofabookcalledTheBossesSpeak.Foreachquestion23-28,choosethecorrectanswer.Markletter
ReadthefollowingreviewsofabookcalledTheBossesSpeak.Foreachquestion23-28,choosethecorrectanswer.Markletter
•ReadthefollowingreviewofabookcalledTheBossesSpeak.•Foreachquestion(23-28),choosethecorrectanswer.•Marko
•ReadthefollowingreviewofabookcalledTheBossesSpeak.•Foreachquestion(23-28),choosethecorrectanswer.•Marko
•ReadthefollowingreviewofabookcalledTheBossesSpeak.•Foreachquestion(23-28),choosethecorrectanswer.•Marko
随机试题
A.疏肝解郁B.清热化痰C.调和冲任D.益气养阴E.清热解表肉瘿伴急躁易怒、汗出心悸、失眠多梦、形体消瘦,其治法是()
粪便外带鲜血,表示出血可能在()
在古代欧洲,有过这样一首诗:那时候,卜面的青天还没有称呼,下面的大地也没有名字,其阿玛特(即海洋)是大家的生母,万物都和水连在一起。这首诗体现的是()。
班轮运费计收标准中的“W/MPlusAdVal”是指班轮公司计收运费时应按其中较高者计收。()
通常股票的有效期与股份公司的存续期间相联系,两者是并存的关系。()
在成本法下,当被投资企业发生盈亏时,投资企业一般不做账务处理;当被投资企业宣告分配现金股利时,投资企业均应将分得的现金股利确认为投资收益。( )
下列不属于质性研究通常运用的方法的是
已知球面上过A、B、C三点的截面到球心的距离是球半径的一半,且AB=BC=CA=2,则球表面积为()
设矩阵Am×n的秩为r(A)=m<n,Im为m阶单位矩阵,则
Therearecockroaches(蟑螂)everywhereonEarthexcepttheplacesthatarecoveredwithice.Scientistshavediscoveredabout3,50
最新回复
(
0
)