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1、1 地球的形状近似于球体The earths shape is nearly special. 2 它的周长约为25000 英里，其两极直径约为7900 英里，赤道直径为7927 千米 It has a circumference of approximately 25000 miles(40000km), a polar diameter of about 7900 miles (12714km), and an equator diameter of 7927 miles(12756km). 3 地球内部的三大圈层是地核、地幔和地壳。 The three main layers of th
2、e earths interior are core mantle and crust. 4 地核的直径大约为4300 英里（ 6900 千米），其主要成分极可能是铁。The diameter of the core is about 4300 miles (6900km), and iron is probably its chief ingredient. 5 由于地核的体积接近（地球体积的）16%，总体看来，地壳实际上只占地球的一个非常小的部分。 The core consists of an inner part that is believed to be solid and an
3、outer part that appears fluid. 6 地质年代是用来描述地球历史事件的时间单位和各种地质事件发生的时间。The geologic time is a unit of time used to describe the historic events of the earth and the time in which different geologic events take place. 7 它包含两方面的含义:其一是指各地质事件发生的先后顺序，称为相对地质年代；其二是指各地质事件从发生到现今的时间段，称为绝对地质年代。It has two implicatio
4、ns: the time sequence of the geological events called a relative time and the time span from the occurrence of the events to the present referred to as the absolute time. 8 这两方面结合，才构成对地质事件及地球、地壳演变时代的完整认识，地质年代表正是在此基础上建立起来的。 The integration of the two measurements makes possible an overall understandi
5、ng of the geologic events, the earth and the development of the crust just based on which the geologic time scale comes into being. 9 全球变暖，世界各地的温度升高，正在加快侵蚀的速度。Global warming, the increase of temperature around the world, is speeding erosion. 10 气候的变化也与更频繁、更剧烈的风暴联系起来。The change in climate has been li
6、nked to more frequent and more severe stoms. 11 伴随着飓风和台风后的风暴潮可能侵蚀数英里的海岸线和沿海栖息地。Storm surges following hurricanes and typhoons erode miles of coastline and coastal habitat. 12 这些沿海地区有家园、企业，以及经济上重要的产业，比如渔场。Homes, businesses and economically important industries, such as fisheries, settled dowm along t
7、hese areas. 13 温度的升高也迅速融化着冰川，这就造成海平面上升的速度超出了生物可以适应的程度The rise in temperature is also quickly melting glacier, which causes the sea level to rise faster than organisms can adapt to it. 14 上升的海平面会更迅速地侵蚀沙滩。The rising sea erodes sandbeaches much more quickly. 15 据估计，海平面上升810 厘米引起的侵蚀将足矣威胁到建筑物、下水道系统、道路和隧道
8、。It is estimated that a rise in sea level of 8 to 10 centimeters will lead to enough erosion to threaten the safely of buildings, sewer systems, roads and tunnels. 16石英是一种分布很广的矿物，其丰度居第二位。A very widespread mineral,quartz is the second-most abundant. 17 石英是一种特殊矿物，是氧化硅类中唯一常见的矿物。Quartz is a specific min
9、eral,the only common one of the silica group. 18 从化学上说， 氧化硅是SiO2，由此可见， 石英是完全由两种最丰富的化学元素组成的化合物。Chemically,silica is SiO2.Thus,quartz is a compound composed,entirely of the two most abundant chemical elements. 19 在大的纯晶体中，石英类似无色玻璃；但是少许杂质就会赋予它多种多样的颜色。In large pure crystal,quartz resembles colorless glas
10、s. 20 而某些细小的结晶变化，如燧石， 可能是不透明的，并具有油脂光泽Some minutely crystalline varieties,such as flint, may lead to be opaque and of a resinous luster. 21 火成岩也称岩浆岩，来源于拉丁文ignis，意为火焰，一般是由地下深处炽热的熔岩和熔融体在地下或地表冷却凝固而成Igneous rocks, also called magmatic rock and derived from the Latin word ignis meaning fire, are formed be
11、low or on the surface of the earth through the cooling and solidification of hot magma orlava at depth. 22 火成岩分为侵入岩和喷出岩。现在已经发现700 多种类型的岩浆岩，它们中的大部分形成于地壳表面以下的Igneous rocks can be grouped into intrusive and extrusive rocks. Over 700 types of igneous rocks have been found, most of them having formed ben
12、each the surfaceo f Earths crust. 23 花岗岩、安山岩及玄武岩是常见的例子Granite, andesite and basalt are familiar examples. 24 一般来说，火成岩易沿一些大陆板块边缘的火山区生的Generally, igneous rocks are likely to occur in volcanic field along the margin of some continental plates. 25 沉积物是通过像流水、海浪、洋流、风和冰川这样一些地质营力进行搬运和沉降或沉淀下来的。The sediments
13、have been transported and dropped or precipitated by such geologic agents as running waters, ocean waves, ocean currents, winds and glaciers. 26 有的岩石碎屑呈磨圆状，有的则呈棱角状。这种特征取决于搬运距离的远近和其他因素。Some of the rock fragments may be rounded, others are angular. Such features depend upon the distance of transportat
14、ion and other factors. 27 在组成地壳的构造板块中，其中两个板块沿它们的边界互相挤压便形成了褶皱山系。Fold mountains are formed when two of the tectonic plates that make up the Earths crust push together at their border. 28 巨大的压力迫使板块的边缘发生弯曲和向上隆起形成一系列的褶皱。The extreme pressure forces the edges of the plates upwards into a series of folds. 2
15、9 褶皱山系通过所谓的“造山运动 “ 而形成Fold mountains are created through a process called “orogeny“. 30 因为板块每年只位移几厘米，因而一次造山运动形成一个山脉需要数百万年。Because plates move only several centimeters every year, creating a mountain would take millions of years of an orogenic event. 31 褶皱山系是地球上最常见的山脉类型。其他类型有火山山脉、侵蚀山脉和断块山。Fold mounta
16、ins are the most common type of mountains on Earth. Other types of mountains are volcanic mountains, erosional mountains and fault-block mountains. 32 火山活动可形成火山山脉。Volcanoes create volcanic mountains. 33 侵蚀山的产生是由于风和水剥蚀掉了陆地中松软的部分而留下了坚硬的岩丘。Erosional mountains are produced as wind and water wear away soft portions of land and leave hard rocks. 34 断块山形成于大陆地壳发生位移的部位。Fault-block mountains are formed in the areas where the Earths crust are moving. 35 19 世纪末地质学家认为，地球的主要特征是一成不变的。In the late 19th c
