首页
登录
职称英语
Rocks which have solidified directly from molten materials are called igneou
Rocks which have solidified directly from molten materials are called igneou
游客
2025-05-06
38
管理
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. [br] 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://tihaiku.com/zcyy/4064521.html
相关试题推荐
Rockswhichhavesolidifieddirectlyfrommoltenmaterialsarecalledigneou
Acorpsofso-calledbarefootdoctorsaretrainedinhygiene,preventivemedicin
Theinvisibleraysofthe______beyondthevioletendarecalledtheultraviolet
Moderntechnologyandsciencehaveproducedawealthofnewmaterialsandne
Moderntechnologyandsciencehaveproducedawealthofnewmaterialsandne
Moderntechnologyandsciencehaveproducedawealthofnewmaterialsandne
Cultureshockmightbecalledan【1】diseaseofpeoplewhohavebeensuddenly【
Cultureshockmightbecalledan【1】diseaseofpeoplewhohavebeensuddenly【
Cultureshockmightbecalledan【1】diseaseofpeoplewhohavebeensuddenly【
Cultureshockmightbecalledan【1】diseaseofpeoplewhohavebeensuddenly【
随机试题
[originaltext]M:Whydon’tyoutrytofinishyourhomework?I’llcookyouthelu
Advertisingisaformofselling.Forthousandsofyearstherehavebeenind
Theaccidenthappenedin[br][originaltext]Maskedassailantswithgrenades
AsthewindiestcountryinEurope,theUnitedKingdom’swindpowerpotential
施工单位填写的地下工程防水效果检查记录应一式()份。A.二 B.三 C.四
从SF6气体钢瓶引出气体时,当瓶内压力降至9.8×104Pa(1个大气压)时,即
证券交易的公开原则其核心要求是实现()。 A.证券账户资料的公开化B.交易
专业监理工程师对施工控制测量成果及保护措施的检查、复核,不包括( )。A.施工单
患者男,27岁。7天来全身皮肤出血点伴开龈出血来诊。化验PLT35×10/L,临
动脉导管未闭时,下列哪一项体征一般是不存在的A.脉压增宽 B.胸骨左缘第2、3
最新回复
(
0
)