地质英语(科技英语)4.doc

一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 earths 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 down 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 become 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 gneiss or schist. Limestone, a sedimentary rock, when subjected to heat and pressure may become marble, a metamorphic rock. Shale under pressure becomes slate.1 The primary purpose of the passage is to A differentiate between and characterize igneous and sedimentary rocksB explain the factors that may cause rocks to change in formC show how the scientific names of rocks reflect the rocks compositionD define and describe several diverse kinds of rocksE explain why rocks are basic parts of the earths structure2 All of the following are sedimentary rocks EXCEPT A shaleB gravelC sandD limestoneE schist3 The passage would be most likely to appear in a A technical article for geologistsB teaching manual accompanying an earth science textC pamphlet(小册子) promoting conservation of natural resourcesD newspaper feature explaining how oil is foundE nonfiction book explaining where to find results 4 The relationship between igneous and sedimentary rocks may best be compared to the relationship between A leave and compost(堆肥)B water and landC DNA and heredity(遗传)D nucleus(细胞核) and cell wallE sand and clay5 The passage contains information that would answer which of the following questions?I Which elements form igneous rocksII What produces sufficient pressure to alter a rock?III Why is marble called a metamorphic rock?A I only B III only C I and II only D II and III only E I, II, and III二Hydrogeology is a science dealing with the properties, distribution, and circulation of water on the surface of the land, in the soil and underlying rocks, and in the atmosphere. The hydrologic cycle, a major topic in this science, is the complete cycle of phenomena through which water passes, beginning as atmospheric water vapor, passing into liquid and solid form as precipitation, thence along and into the ground surface, and finally again returning to the form of atmospheric water vapor by means of evaporation and transpiration.The term “geohydrology is sometimes erroneously used as a synonym for “hydrogeology”. Geohydrology is concerned with underground water. There are many formations that contain water but are not part of the hydrologic cycle because of geologic changes that have isolated them underground. These systems are properly termed geohydrologic but not hydrogeologic. Only when a system possesses natural or artificial boundaries that associate the water within it with the hydrologic cycle may the entire system properly be termed hydrogeologic. 1 The authors primary purpose is most probably to A present a hypothesis(假说)B refute(驳斥) an argumentC correct a misconception(误解)D predict an occurrenceE describe an enigma(迷)2 It can be inferred that which of the following is most likely to be the subject of study by a geohydrologist?A Soft, porous rock being worn away by a waterfallB Water depositing minerals on the banks of a gorge through which the water runsC The trapping of water in a sealed underground rock cavern through the action of an earthquakeD Water becoming unfit to drink through the release of pollutants into it from a manufacturing plantE The changing course of a river channel as the action of the water wears away the rocks past which the river flows3 The author refers to “many formations”(正文画线处)primarily in order to A clarify a distinctionB introduce a subjectC draw an analogy(类比)D emphasize a similarityE resolve a conflict 14 GROUND WATER HYDROLOGYThe science of hydrology would be relatively simple if water were unable to penetrate below the earths surface. Harold E. ThomasGround-water hydrology is the subdivision of the science of hydrology that deals with the occurrence, movement, and quality of water beneath the Earths surface. It is interdisciplinary in scope in that it involves the application of the physical, biological, and mathematical sciences. It is also a science whose successful application is critical importance to the welfare of mankind. Because ground-water hydrology deals with the occurrence and movement of water in an almost infinitely complex subsurface environment, it is in its most advanced state, one of the most complex of the sciences. On the other hand, many of its basic principles and methods can be understood readily by non-hydrologists and used by them in the solution of ground-water problems. The purpose of this report is to present these basic aspects of ground-water hydrology in a form that will encourage more widespread understanding and use.The ground-water environment is hidden from view except in caves and mines, and the impression that we gain even from these are, to a large extent, misleading. From our observations on the land surface, we form an impression of a “solid” Earth. This impression is not altered very much when we enter a limestone cave and see water flowing in channel that nature has cut into what appears to be solid rock. In fact, from our observations both on the land surface and in caves, we are likely to conclude that ground water occurs only in underground rivers and “veins”. We do not see the myriad openings that exist between the grains of sand and silt, between particles of clay or even along the fractures in granite. Consequently, we do not sense the presence of the openings that, in total volume, far exceed the volume of all caves.R.L.Nace of the U.S. Geological Survey has estimated that the total volume of the subsurface openings (which are occupied mainly by water, gas and petroleum) is on the order of 251,000km3(125,000mi3 )beneath the United States alone. If we visualize these opening as forming a continuous cave beneath the entire surface of the United States, its height would be about 57m (186ft). the openings, of course, are not equally distributed, the result being that our imaginary cave would range in height from 3m(10ft) beneath the Piedmont Plateau along the eastern seaboard to about 2,500m(8200ft) beneath the Mississippi delta. The important point to be gained from this discussion is that the total volume of openings beneath the surface of the United States, and other land area of the world, is very large.Most subsurface openings contain water, and the importance of this water to mankind can be readily demonstrated by comparing its volume with the volumes of water in other parts of the hydrosphere. Estimates of the volumes of water in the hydrosphere have been made by the Russian hydrologist M.I. L vovich and are given in a book recently translated into English. Most water, including that in the oceans and in the deeper subsurface openings, contains relatively large concentrations of dissolved minerals and is not readily usable for essential human needs. We will, therefore, concentrate in this discussion only on freshwater. The accompanying table contains Lvovichs estimates of the freshwater in the hydrosphere, not surprisingly, the largest volume of freshwater occurs as ice in glaciers. On the other hand , many people impressed by the “solid” Earth are surprised to learn that about 14 percent of all freshwater is ground water and that, if only water is considered, 94 percent is ground water.Ground-water hydrology, as noted earlier, deals not only with the occurrence of underground water but also with its movement. Contrary to our impressions of rapid movement as we observe the flow of streams in caves, the movement of most ground water is exceedingly slow. The truth of this observation becomes readily apparent from the table, which shows, in the last column. The rate of water exchange or the time required to replace the water now contained in the listed parts of the hydrosphere. It is especially important to note that the rate of exchange of 280 years for fresh ground water is about 1/9,000 the rate of exchange of water in rivers.Subsurface openings large enough to yield water in a usable quantity to wells and springs underlie nearly every place on the land surface and thus make ground water one of the most widely available natural resources. When this fact and the fact that ground water also represents the reservoir of fresh water readily available to man are considered together, it is obvious that the value of ground water, in terms of both economics and human welfare, is incalculable. Consequentially, its sound development, diligent conservation, and consistent protection from pollution are important concerns of everyone. These concerns can be translated into effective action only by increasing our knowledge of the basic aspects of ground-water hydrology. 15. GROUND WATER RESOURCES PLANNING Until the turn of the century, the development of surface and ground water resources has not had a major effect on the overall availability of such resources. The reason was that the technologies available for dam, canal and well construction have not generally been required to handle large quantities of water. As regards ground water, for reasons of convenience, only one source was developed at a time-generally to a modest extent to serve local needs by means of a small dam, a diversion canal, a canal fed by a spring, an underground drainage gallery or a well. The technological breakthroughs powered by increased energy consumption, which were developed in this century, have made it possible to handle increasing quantities of water through them, construction of large storage dams, extended diversion canals, and well-fields exploited by means of high-yield motorized pumps. As a result, the water cycle has been altered. In addition, the rising tide of chemical products and chemical wastes, especially the wide-spread use of fertilizers and pesticides in agriculture, threatens water quality. Good quality water is becoming a rare and expensive commodity in some places, while water needs are increasing. In water management, as a fundamental aspect ground water resources planning must be considered. The basic approach to planning is to determine (i) the needs, (ii) the resources, and (iii) ways to develop the resources to meet needs, on the basis of the technologies, financial and human resources, which are available. Until recently, a water resources planning exercise was applied mainly to political and geographical boundaries such as a country or a region, or a river basin. However, this concept is now shifting to economic considerations. Such is the case, for example, of selecting for study metropolitan areas or large industrial areas. One cannot underestimate the close interrelationships which exist between a national plan and a water resources planning exercise. Together with energy, water is one of the major factors of economic development. A development plan, especially in a water-short area, such as an arid belt, or a flat area underlain by hard rocks without major surface streams, can not be drawn unless a clear idea of water availability and costs has been reached. Conversely, the availability of water does not imply that it will be developed in the foreseeable future. Development stems from government policy which takes into account socioeconomic factors and political options as well as natural resources availability and technological opportunities. The United Nations has recognized this fact and has considered it necessary to include water resources planners in interdisciplinary planning teams within the frame work of several economic planning projects.Assessing water needs In any plan, priorities and goals have to be defined. As far as water resources development is concerned, some guidelines were drawn up at the 1977 International Water Conference of Mar del Plata (Argentina). It was recognized that basic human needs for drinking, cooking and domestic water had first priority with the needs of domestic and wild animals, and irrigation coming second. As a result, an International Drinking water Supply and Sanitation Decade was launched in December 1980, its objective being adequate water and sanitation for all by the year 1990. It now appears that in many countries this ambitious goal will not be reached by 1990. It is therefore essential to forecast water demand on the basis of needs which can effectively be met, taking into account financial and human resources and technological options. Related procedures and approaches are dealt with in a United Nations Publication: The Demand for Water: Procedure and Methodologies for projecting Water Demands in the context of Regional and National Planning, which followed a U.N. symposium on this subject, held in Budapest in 1972. An evaluation of future demand should be based on the results of recent comprehensive survey of water users. Such a survey may be difficult; as for any other survey, the time and resources allocated for its execution should be kept to a minimum. In many United Nations executed projects, an evaluation of the present and future levels of water utilization has been made. This was the case. in ground water projects focusing on metropolitan areas of Center America such as El Salvador, Guatemala, Costa Rica and Honduras, as well as in projects for economic planning in India. Evaluating ground water availability. At the same time that water needs are being assessed water availability has to be evaluated as to quantity, quality and costs for various sources of water. This should be done over a number of years. While surface water surveys are relatively easy and inexpensive, ground water surveys are more complex and costly as they involve test drilling, pumping, and geophysical surveys, in addition to continuous water data collection through yield and water level measurements on springs and wells. The cost of any survey is closely related to the number of observation sites, frequency of measurement, and technology used. In developing countries surveys should not be designed independently of practical objectives in term of socioeconomic benefits, and without considering means to minimize costs. The United Nations has carried out a large number of resources surveys on developing countries. It has also helped in the organization of data banks. However, assessing groundwater availability goes far beyond the stage of data collection. It involves the study of ground water flow, assessment of hydrogeological balance, and ground water equilibrium in aquifers. Forecasts of future uses of water resources on the basis of various scenarios for exploitation should also be undertaken. These can be achieved by means of mathematical models. Not only has the United Nations developed the use of such models through its projects; it has also helped to transfer technology to a number of countries through large scale projects and short-term advisory services. Water resources interrelationships. The interrelationships between surface water and ground water resources appear clearly in the representation of the water cycle. They can also be accentuated through man-made interventions. It is well known that extensive pumping from aquifers may have a negative impact on the yield of springs and surface streams; conversely, extensive irrigation projects may have water-logging and salinization effects. It is therefore inappropriate to separately consider surface water and ground water resources through hydro-schizophrenic surveys and development schemes, It should also be kept in mind that in this interrelationship, energy considerations may play an important role. The development of ground water resources may occur using electric pumping within the frame work of integrated hydropower ground water projects. The rising cost of petroleum products may, on the other hand, preclude or put an end to tube well irrigation projects utilizing petrol or diesel fuel-powered pumping stations as surface water irrigation becomes a more attractive alternative. This has been case in th