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Unit 1 Basic Geology Lesson 1 Geology Earth science also known as geoscience, the geosciences or the Earth sciences, is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, the Earth being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth sciences. The al discipline of Earth Sciences may include the study of the atmosphere, oceans and biosphere, as well as the solid earth. Geology is generally categorized within the geosciences. Geology from the Greek，geo, “earth“ and, logos, “speech“ is a natural science, which studies the geology science of the earths history, composition, and structure, and the associated processes. It draws upon chemistry, biology, physics, astronomy, and mathematics notably statistics for support of its ulations. Geology is a very complex science. There are many branches of Geology, which can be grouped under the major headings of physical and historical geology. Physical Geology Physical geology includes mineralogy, the study of the chemical composition and structure of minerals; petrology, the study of the composition and origin of rock; geomorphology, the study of the origin of lands and theirs modification by dynamic processes; geochemistry, the study of the chemical composition of the earth materials and the chemical changes that occur within the earth and on its surface; geophysics, the study of the behavior of rock materials and in response to stresses and according to the principles of physics; sedimentology, the science of the erosion and deposition of rock particles by wind, water, or ice; structural geology, the study of the forces that de the earth’s rocks and the description and mapping of deed rock bodies; economic geology, the study of the exploration and recovery of natural resources, such as ores and petroleum; and engineering geology, the study of the interaction of the earth’s crust with human-made structures such as tunnel, mines, dams, bridges, and building foundations. Historical geology Historical geology deals with the historical development of the earth from the study of its rocks. They are analyzed to determine their structure, composition, and interrelationships and are examined for remains of past life. Historical geology includes paleontology, the systematic study of past life s; stratigraphy, of layered rocks and their interrelationships; paleogeography, of the locations of ancient land masses and their boundaries; and geologic mapping, the superimposing of geologic ination upon existing topographic maps. Historical geologists divide all time since the ination of the earliest known rocksc,4 billion years ago into four major divisions the Precambrian, Paleozoic, Mesozoic, and Cenozoic eras. Each, except the Cenozoic, ended with profound changes in the disposition of the earth’s continents and mountains and was characterized by the emergence of new s of life. Broad cyclical patterns, which run through all historical geology, include a period of mountain and continent building followed one of erosion and, in turn, by a new period of elevation. Early Geologic Studies Observations on earth structure and processes were made by a number of the ancients, including Herodotus, Aristotle, Lucretius, Strabo, and Seneca. Their individual efforts in the natural history of the earth, however, provided no sustained progress. Their major contribution is that they attributed the phenomena they observed to natural and not supernatural causes. Many of the ideas expressed by these men were not to resurface until the Renaissance. Later Leonardo da Vinci correctly speculated on the nature of fossils as remain of ancient organisms and on the role that rivers play in the erosion of land. Agricola made a systematic study of ore deposits in the early 16th century. Robert Hooke and Nicolaus Steno both made penetrating observations on the nature of fossils and sediments. Evolution of Modern Geology Modern geology began in the 18th century, when field studies by the French mineralogist J.E.Guttard and others proved more fruitful than speculation. The German geologist Abraham Gottlob Werner, in spite of the many errors of his specific doctrines and the diversion of much of his energy into a fruitless controversy in which he maintained that origin of all rocks was aqueous, pered a great service for the science by demonstrating the chronological succession of rocks. In 1795 the Scottish geologist James Hutton laid the theoretical foundation for much of the modern science with his doctrine of uniitarianism, first popularized by the British John Playfair. Largely through the work of sir Charles Lyell, this doctrine replaced the opposing one of catastrophism. Geology in the 19th century was influenced also by the work of Charles Darwin and enriched by the researches of the Swiss-American Louis Agassiz. In the 20th century, geology has advanced at an ever-increasing pace. The unraveling of the mystery of atomic structure and the discovery of radioactivity allowed profound advances in many phases of geologic research. Important discoveries were made during the International Geological Year 1957-58, when scientists from 67 nations joined force in investigating problems in all branches of geology. The systematic survey of the earth’s oceans brought radical changes in concepts of crustal evolution. As a result of numerous flyby spacecraft, geological studies have been extended to include remote sensing of other planets and satellites in the solar system and the moon. Laboratory analyses of rocks samples brought back from the moon have provided insight into the early history of near-earth space. On–site analyses of Martian soil samples and photographic mapping of its surface have given clues about its composition and geologic history, including the possibility that Mars once had enough water to oceans. Photographs of the many active volcanoes on Jupiter’s moon Io have provided clues about earth’s early volcanic activity. Geological studies also have been furthered by orbiting laboratories, such as the six launched between 1964 in the Orbiting Geophysical Observatory OGO series and the Polar Orbiting Geomagnetic Survey POGS satellite launched in 1990; remote-imaging spacecraft, such as the U.S. Landsat program Landsat7, launched in 1999, was the most recent and French SPOT series SPOT4, launched in 1988,was the most recent in the program; and geological studies on space shuttle missions. New Words and Phrases 1. mineralogy [minErQlEdZi] n. 矿物学 2. petrology [pitrOlEdZi] n. 岩石学 3. geomorphology [.dZiEumOfOlEdZi] n. 地貌学 4. geochemistry [.dZiEukemistri] n. 地球化学 5. geophysics [.dZiEufiziks] n. 地球物理学 6. sedimentology [sedimEntOlEdZi] n. 沉积学 7. structural geology 构造地质学 8. economic geology 经济地质学（矿床学） 9. paleontology [.pQliOntOlEdZi] n. 古生物学 10. stratigraphy [strEtigrEfi] n. 地层学 11. paleogeography [.pQlIEUdZiOgrEfi] n. 古地理学 12. Precambrian [prikQmbriEn] n. adj. 前寒纪 13. Paleozoic [pQliEzEuk] n. adj. 古生代（界） 14. Mesozoic [.mesEuzEuik] n. adj. 中生代（界）（的） 15. Cenozoic [.sinEzEuik] n. adj. 新生代（界）（的） 16. catastrophism [kEtQstrEfizEm] n. 灾难论 17. remote sensing n.遥感 18. space shuttle 航天飞机 19. Herodotus [hirOdEtEs]（希腊历史学家）希罗多德（约公元前485-约公元前425） 20. Werne 维尔纳1750-1817 德国地质学家、矿物学家，水成论的创立者 21. uniitarianism [.juni.fOmEtCEriEnizEm] n. 均变论 22. Aristotle [QristOtl] 亚里士多德（公元前322-公元前384古希腊大哲学家，科学家） 23. Renaissance [rEneisEns] n. 文艺复兴（时期） 24. Charles Darwin [dAwin] 查尔斯 达尔文，英国博物学家，进化论创立者 25. Landsat [lQndsQt] n. （美国）地球资源（探测）卫星 26. aqueous [QkwiEs；eikwiEs] adj.含水的，似水的 Translations the mantle and core are each divided into two parts. Although the core and mantle are about equal in thickness, the core actually s only 15 percent of the Earths volume, whereas the mantle occupies 84 percent. The crust makes up the remaining 1 percent. The Earth’s Crust and the Moho Because the crust is accessible to us, its geology has been extensively studied, and therefore much more ination is known about its structure and composition than about the structure and composition of the mantle and core. Within the crust, intricate patterns are created when rocks are redistributed and deposited in layers through the geologic processes of eruption and intrusion of lava, erosion, and consolidation of rock particles, and solidification and recrystallization of porous rock. By the large-scale process of plate tectonics, about twelve plates, which contain combinations of continents and ocean basins, have moved around on the Earths surface through much of geologic time. The edges of the plates are marked by concentrations of earthquakes and volcanoes. Collisions of plates can produce mountains like the Himalayas, the tallest range in the world. The plates include the crust and part of the upper mantle, and they move over a hot, yielding upper mantle zone at very slow rates of a few centimeters per year, slower than the rate at which fingernails grow. The crust is much thinner under the oceans than under continents. The boundary between the crust and mantle is called the Mohorovicic discontinuity or Moho; it is named in honor of the man who discovered it, the Croatian scientist Andrija Mohorovicic. No one has ever seen this boundary, but it can be detected by a sharp increase downward in the speed of earthquake waves there. The explanation for the increase at the Moho is presumed to be a change in rock types. Drill holes to penetrate the Moho have been proposed, and a Soviet hole on the Kola Peninsula has been drilled to a depth of 12 kilometers, but drilling expense increases enormously with depth, and Moho penetration is not likely very soon. The Earth’s Mantle Extending to a depth of c.2, 900 km, the mantle probably consists of very dense average c.3.9 rock rich in iron and magnesium minerals. Although temperatures increase with depth, the melting point of the rock is not reached because the melting temperature is raised by the great confining pressure. At depths between c.100 and c.200 km in the mantle, a plastic zone, called the asthenosphere, is found to occur. Presumably the rocks in this region are very close to melting, and the zone represents a fundamental boundary between the moving crustal plates of the earth’s surface and the interior regions. The molten magma that intrudes upward into crustal rocks or issues from a volcano in the from of lava may owe its origin to radioactive heating or to the relief of pressure in the lower crust and upper mantle caused by earthquake faulting of the overlying crustal rocks.⑤ Similarly, it is thought that the heat energy released in the upper part of mantle has broken the earth’s crust into vast plates that slide around on the plastic zone, setting up stresses along the plate margins that result in the ation of folds and faults. The Earth’s Core Though to be composed of iron and nickel, the dense c.11.0 core of the earth lies below mantle. The abrupt disappearance of direct compressional earthquake waves, which cannot travel though liquids, at depths below c.2, 900 km indicates that the outer2, 200 km of the core are molten. It is thought, however, that the inner 1,260 km of the core are solid. The outer core is thought to be the source of the earth’s magnetic field In the ‘dynamo theory’ advanced by W.M.Elasser and E. Bullard, tidal energy or heat is converted to mechanical energy in the of currents in the liquid core; this mechanical energy is then converted to electromagnetic energy, which we see as the magnetic field. The Earth’s Age the earth is estimated to be 4.5 billion to 5 billion years old, based on radioactive dating of lunar rocks and meteorites, which are thought to have ed at the same time. The origin of the earth continues to be controversial. Among the theories as to its origin, the most prominent are gravitational condensation hypotheses, which suggest that the entire solar system was ed at one time in a single series of processes resulting in the accumulation of diffuse interstellar gases and dust into a solar system of discrete bodies. Old and now generally discredited theories invoked extraordinary events, such as gravitational disruption of a star passing close to the sun or the explosion of a companion star to the sun. New Words and Phrases 1. geology [dZiOlEdZi] n. 地质学 2. astronomy [EstrOnEmi] n. 天文学 3. solar system n. 太阳系 4. gravitation [;grAviteiSEn] n. 地心吸力 5. celestial body [silestSEl] n. 天体 6. equator [ikweitE] n. 赤道 7. altitude [Qltitjud] n. 海拔高度 8. meteorite [mitjEtait] n. 陨石 9. con
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