第一课1.科学家认为地球由几层组成Scientists think the earth is composed of / consists of / is made up of several layers.2.地球的固态部分称为岩石圈。

The solid parts of the earth is called / referred to as lithosphere.3.地质学家发现大部分海洋下地壳厚4~10英里。

Geologists found that the crust under the ocean is 4-10 miles deep / to a depth of 4-10 miles / as thick as 4-10 miles / 4-10 mile-thick.4.水和空气在地球历史上是作用于地球表面的最重要的因素。

Water and air are exceedingly / significant imporant factors in acting on the surface of the earth in the earth history.5.大气圈是由环绕地球固体和液体部分的气体组成。

The atmosphere is composed of the air which surroounds the solid and liquid parts of the earth.第二课1.大约地壳重量的75%是由氧和硅这两种元素组成的。

Approximately / About 75% of the crust’s weight is composed of/ is made of / consists of the elements of oxygen and silicon.★compose , consist of , comprise , constitute 这组动词的一般含义为“组成”或“构成”。

▪ compose 在表示“由……材料构成”时，见于被动语态；在用于主动语态时，一般它所表示的“构成”或“组成”总包含着融合为一，而且主语或者是复数名词或者是集体名词。

Concrete is composed of cement, sand and gravel mixed with water.混凝土由水泥、砂、石子与水掺和而构成。

England, Scotland and Wales compose the island of Great Britain.英格兰、苏格兰和威尔士构成大不列颠岛。

Mere facts, badlly stated, do not compose a good book.仅仅有资料，如果陈述得很糟糕，并不能组成一本好书；▪ consist of 的含义与被动语态的compose 相同Though the costume consists only of a sheet, it was very effective.虽然那件化装服装仅由一条床单组成，但效果很好。

▪ comprise 在表示“构成”时，其内涵是“包括”或“覆盖”These houses do not comprises all his property.这些房产并没有构成他的全部财产。

The committee comprises men of widely different views.这个委员会由见解甚为悬殊的人组成。

▪ constitute 的主语可以是复数名词也可以是单数名词，所“构成”的事物在属性和特征上，亦或在组织上，与组成成分是一致的This growing poverty in the midst of growing poverty constitutes a permanent menace to peace.在这种不断增长的贫困中正在增长着的贫困，构成了对和平的永久的威胁。

Seven days constitutes a week.七天构成一个星期。

2.硅酸盐晶体中最基本的单位称之为硅氧四面体。

The most basic unit of silicate crystal is referred to as / is known as silicon-oxygen tetrahedron.3.矿物的硬度主要取决于矿物空间格子中原子和离子之间化学键的强度。

The hardness of/ The scale of mineral is determined mainly by / depends upon the strength of the chemical bonds between atoms and ions in the spacial lattice/in its space lattice.4.矿物沿着一定的方向破裂成光滑面的性质称为解理。

The characteristic / feature that a mineal splits / breaks into smooth plats / planes/ corrupts into smooth surface along certain directions is called cleavage.5.虽然已经发现了2000多种矿物并且进行了科学的描述，但是它们当中的大多数在地壳中占的比例很少而且很难遇到。

While more than 2000 kinds of minerals have been discovered and scientifically described , the most / majority of them account for little proportion in the crust and can be found hardly/most of them occupy little scale in the crust and can hardly be found.第三课1.总的来说，变质岩的特征取决于变质因素的种类和强度以及母岩本身的性质。

In a word / Generally , the nature / characteristics /properties of metamorphic rocks depend upon the types and strengths of the matamorphic factors ,as well as the nature of parent rocks themselves.或In a word, the features of metamorphic rocks depend on the types and strengths of the metamorphic factors, as well as the nature of parent rock itself.2.沉积岩大约占地壳的8%，然而它们却覆盖着全部陆地的75%。

Sedimentary rocks occupies only 8% of the crust, but covers 75% of the total land.3.喷发过程是宁静的还是爆发的，其主要决定因素是岩浆的温度粘度以及岩浆中包含气体的数量.Whether the course of eruption is quiet or volcanic depends largely upon the temperature and viscosity of the magma , as well as the amount of gas contained in / and also on the amount of gas it contained.4.大多数变质岩可以根据其结构与岩浆岩，沉积岩区分开来。

Most metamorphic rocks can be identified / separated from/ divided from magmatic rocks and sedimentary rocks in terms of its structure.5.在沉积岩中可以找到化石。

Fossils can be found in sedimentary rocks.第四课1.化石是古代生命存在的证据。

Fossils are the evidences of the existence of ancient organisms/lives.2.化石能提供某一地区古地理和古气候变化的线索。

Fossils can provide/offer with the clues to the past geographic and climatic changes in a certain area/region.3.标准化石能帮助地质工作者测定岩层的相对年代。

Index / Standard fossils can help geologists determine the relative areas.4.古生物学时地质学中有关古代生命研究的一个分支学科，它是以研究化石为基础的。

Paleontology is one of subdivisions of geology on the study of ancient organisms ,which is based on study of fossils .5.由于人们发现化石能当作时间的指示标志，所以它成了对比不同地层的相近年代的岩层的最佳手段。

Because people found fossils can be regarded as time indicators, so it became the best means of comparing the different strata with a similar age rocks.或Because people find that fossils can be regarded as time indicators, they become the best methods in comparison between strata in different area and similar eras.6.化石也是重要的环境指示标志。

Fossil is also an importantly environmental indicator .或Also fossils are important/significant environmental indicators.第五课1.每一个地质年代中发现的化石有较大的差异。