GEOSCIENCE AND EVERYDAY LIFE

CONCEPT

How can learning about rocks help us in our daily lives? The short answer is that geology and the related geologic sciences (sometimes referred to collectively as geoscience ) give us a glimpse of the great complexity inherent in the natural world, helping us appreciate the beauty and order of things. This, in turn, makes us aware of our place in the scheme of things, so that we begin to see our own daily lives in their proper context. Beyond that, the study of geoscientific data can give us an enormous amount of information of practical value while revealing much about the world in which we dwell. The earth sciences are, quite literally, all around us, and by learning about the structures and processes of our planet, we may be surprised to discover just how prominent a place geoscience occupies in our daily lives and even our thought patterns.

HOW IT WORKS

Why Study Geoscience?

One of the questions students almost always ask themselves or their teachers is "How will I use this?" or "What does all this have to do with everyday life?"It is easy enough to understand the application of classes involved in learning a trade or practical skill—for example, wood shop or a personal finance course. But the question of applicability sometimes becomes more challenging when it comes to many mathematical and scientific disciplines. Such is the case, for instance, with the earth sciences and particularly geoscience. Yet if we think about these concerns for just a moment, it should become readily apparent just why they are applicable to our daily lives.

After all, geoscience is the study of Earth, and therefore it relates to something of obvious and immediate practical value. We may think of a hundred things more important and pressing than studying Earth—romantic involvements, perhaps, or sports, or entertainment, or work (both inside and outside school)—yet without Earth, we would not even have those concerns. Without the solid ground beneath our feet, which provides a stage or platform on which these and other activities take place, life as we know it would be simply impossible. Our lives are bounded by the solid materials of Earth—rocks, minerals, and soil—while our language reflects the primacy of Earth in our consciousness. As we discuss later, everyday language is filled with geologic metaphors.

Defining Geoscience

The geologic sciences—geology, geophysics, geo-chemistry, and related disciplines—are sometimes referred to together as geoscience. They are united in their focus on the solid earth and the mostly nonorganic components that compose it. In this realm of earth science, geology is the leading discipline, and it has given birth to many off-shoots, including geophysics and geochemistry, which represent the union of geology with physics and chemistry, respectively.

Geology is the study of the solid earth, especially its rocks, minerals, fossils, and land formations. It is divided into historical geology, which is concerned with the processes whereby Earth was formed, and physical geology, or the study of the materials that make up the planet. Geophysics addresses Earth's physical processes as well as its gravitational, magnetic, and electric properties and the means by which energy is transmitted through its interior. Geochemistry is concerned with the chemical properties and processes of Earth—in particular, the abundance and interaction of chemical elements.

These subjects are of principal importance in this book. Though geology takes the lion's share of attention, geophysics and geochemistry each encompass areas of study essential to understanding our life on Earth: hence we look in separate essays at such geophysical subjects as Gravity and Geodesy or Geomagnetism as well as such geochemical topics as Biogeochemical Cycles, Carbon Cycle, and Nitrogen Cycle.

OTHER AREAS OF GEOSCIENCE.

In addition to these principal areas of interest in geoscience, this book treats certain subdisciplines of geology as areas of interest in their own right. These include geomorphology and the studies of sediment and soil. Geomorphology is an area of physical geology concerned with the study of landforms, with the forces and processes that have shaped them, and with the description and classification of various physical features on Earth.

In contrast to geology, which normally is associated with rocks and minerals, geomorphology is concerned more with larger configurations, such as mountains, or with the erosive and weathering forces that shape such landforms. (See, for instance, essays on Mountains, Erosion, and Mass Wasting.) Erosion and weathering also play a major role in creating sediment and soil, areas that are of interest in the subdisciplines of sedimentology and soil science.

CONTRAST WITH OTHER DISCIPLINES AND SUBDISCIPLINES.

Geoscience is distinguished sharply from the other branches of the earth sciences, namely, hydrologic sciences and atmospheric sciences. The first of these sciences, which is concerned with water, receives attention in essays on Hydrology and Hydrologic Cycle. The second, which includes meteorology (weather forecasting) and climatology, is the subject of the essays Weather and Climate.

In addition to the hydrologic and atmospheric sciences, there are areas of earth sciences study that touch on biology. Essays in this book that treat biosphere-related topics include Ecosystems and Ecology and Ecological Stress. There is one area or set of areas, however, in which geoscience and biology more or less overlap: sedimentology and soil science, since soil is a combination of rock fragments and organic material (see Soil).

The Territory of Geoscience

The organic material in soil—dead plants and animals and parts thereof—has ceased to be part of the biosphere and is part of the geosphere. The geosphere encompasses the upper part of Earth's continental crust, or that portion of the solid earth on which human beings live and which provides them with most of their food and natural resources. (For more about the "spheres," see Earth Systems.)

Later in this essay, we discuss several areas of geoscientific study that take place close to the surface of Earth. Yet the territory of geoscience extends far deeper, going well below the geosphere into the interior of the planet. (For more on this subject, see Earth's Interior.) Geoscience even involves the study of "earths" other than our own; as discussed in such essays as Planetary Science and Sun, Moon, and Earth, there is considerable overlap between geoscience and astronomy.

REAL-LIFE APPLICATIONS

The Primacy of Earth

We may not think about geoscience or earth science much, or at least we may not think that we think about these topics very much—and yet we spend our lives in direct contact with these areas. Certainly in a given day, every person experiences physics (the act of getting out of bed is an example of the third law of motion, discussed in Gravity and Geodesy) and chemistry (eating and digesting food, for instance), but the experience of geoscience is more direct: we can actually touch the earth.

Before the late nineteenth century and the introduction of processed foods, everything a person ate clearly either was grown in the soil or was part of an animal that had fed on plants grown in the soil. Even today, the most grotesquely processed products, such as the synthetic cream puffs sold at a convenience store, still hold a connection to the earth, inasmuch as they contain sugar—a natural product. In any case, most of what we eat (especially in a health-conscious diet) has a close connection to the earth.

GEOSCIENCE AND LANGUAGE.

No wonder, then, that a number of creation stories, including the one in Genesis, depict humankind as coming from the soil—an account of origins reflected in the well-known graveside benediction "Ashes to ashes, dust to dust." Our language is filled with geoscientific metaphors, including such proverbs as "A rolling stone gathers no moss" or "Still waters run deep." (The latter aphorism, despite its hydrologic imagery, actually refers to the fact that in deeper waters, rock formations are, by definition, not likely to be near the surface. By contrast, in order for a "babbling brook" to make as much noise as it does, it must be flowing over prominent rocks.)

Then there are the countless geologic figures of speech: "rock solid," "making mountains out of molehills," "cold as a stone," and so on. When the rock musician Bob Seger sang, in a 1987 hit, about being "Like a Rock" as a younger man, listeners knew exactly what he meant: solid, strong, dependable. So established was the metaphor that a few years later, Chevrolet used the song in advertising their trucks and sport-utility vehicles (including, ironically, a vehicle whose name uses a somewhat less reassuring geologic image: the Chevy Avalanche).

THE GEOMORPHOLOGY OF RELIGIOUS FAITH.

Rocks and other geologic features have long captured the imagination of humans; hence, we have the many uses of mountains in, for instance, religious imagery. There was the mystic mountain paradise of Valhalla in Norse mythology as well as Mount Olympus in Greek myths and legends. Unlike Valhalla, Olympus is a real place; so, too, is Kailas in southwestern Tibet, which ancient adherents of the Jain religion called Mount Meru, the center of the cosmos, and which Sanskrit literature identifies as the paradise of Siva, one of the principal Hindu deities.

There is also Sri Pada, or Adam's Peak, in Sri Lanka, a spot sacred to four religions. Buddhists believe the mountain is the footprint of the Buddha, while Hindus call it the footprint of Siva. Muslims and Christians believe it to be the footprint of Adam. Then there are the countless mountain locales of the Old Testament, including Ararat (in modern Turkey), where Noah's ark ran aground, and Sinai (in the Sinai Desert between Egypt and Israel), where Moses was called by God and later received the Ten Commandments.

The New Testament account of the life of Jesus Christ is punctuated throughout with geologic and geomorphologic details: the temptations in the desert, the Sermon on the Mount, and the Transfiguration, which probably took place atop Mount Tabor in Israel. He was crucified on a hill, buried in a cave, rolled a stone away at his Resurrection, and finally ascended to heaven from the Mount of Olives.

Arts, Media, and the Geosciences

From ancient times rocks and minerals have intrigued humans, not only by virtue of their usefulness but also because of their beauty. On one level there is the purely functional use of rock as a building material, and on another level there is the aesthetic appreciation for the beauty imparted by certain types of rock, such as marble.

Rock is an excellent building material when it comes to compression, as exerted by a great weight atop the rock; in the case of tension or stretching, however, rock is very weak. This shortcoming of stone, which was otherwise an ideal building material for the ancients (given its cheapness and relative abundance in some areas of the world), led to one of history's great innovations in architecture and engineering: the arch. A design feature as important for its aesthetic value as for its strength, the arch owed its physical power to the principle of weight redistribution. Arched Roman structures two thousand or more years old still stand in Europe, a tribute to the interaction of art, functionality, and geoscience.

THE VISUAL ARTS.

The Oxford Companion to the Earth contains a number of excellent entries on the relationship between geoscience and the arts. In the essay "Art and the Earth Sciences," for instance, Andrew C. Scott notes four ways in which the earth sciences and the visual arts (including painting, sculpture, and photography) interact: through the depiction of such earth sciences phenomena as mountains or storms, through the use of actual geologic illustrations or even maps as forms of artwork, through the application of geologic materials in art (most notably, marble in sculpture), and through the employment of geology to investigate aspects of art objects (for instance, determining the origins of materials in ancient sculpture).

In the first category, visual depictions of geologic phenomena, Scott mentions works by unknown artists of various premodern civilizations (in particular, China and Japan) as well as by more recent artists whose names are hardly household words. On the other hand, some extremely well known figures produced notable works related to geoscience and the earth sciences. For example, the Italian artist and scientist Leonardo da Vinci (1452-1519), who happened to be one of the fathers of geology (see Studying Earth), painted many canvases in which he portrayed landscapes with a scientist's eye.

Another noteworthy example of earth sciences artwork and illustration is The Great Piece of Turf (1503), by Leonardo's distinguished contemporary the German painter and engraver Albrecht Dürer (1471-1528). A life-size depiction of grasses and dandelions, Turf belongs within the realm of earth sciences or even biological sciences rather than geoscience, yet it is significant as a historical milestone for all natural sciences.

In creating this work, Dürer consciously departed from the tradition, still strong even in the Renaissance, of representing "important" subjects, such as those of the Bible and classical mythology or history. By contrast, Dürer chose a simple scene such as one might find at the edge of any pond, yet his painting had a tremendous artistic and scientific impact. He set a new tone of naturalism in the arts and established a standard for representing nature as it is rather than in the idealized version of the artist's imagination.

As a result of Dürer's efforts, the period between about 1500 and 1700 saw the appearance of botanical illustrations whose quality far exceeded that of all previous offerings. Thus, he started a movement that spread throughout the world of scientific illustrations in general. Later, such geologists as England's William Smith (1769-1839) would produce maps that are rightly regarded as works of art in their own right (see Measuring and Mapping Earth).

Sometimes geologic phenomena have themselves become the basis for works of art, as Scottpoints out, observing that the modern Americanartist James Turrell once "set out to modify anextinct volcano, the Roden Crater [in northern Arizona], by excavating chambers and a tunnel toprovide a visual experience of varying spatialrelationships, the effects of light, and the perception of the sky." Elsewhere in the Oxford Com panion, other writers show how evidence of a geoscientific influence has appeared in other arts and media, including music.

MUSIC.

In "Music and the Earth Sciences," D. L. Dineley and B. Wilcock offer a fascinating overview of natural formations or materials that have their own musical qualities: for example, the "singing sands" of the Arabian peninsula and other regions, which produce musical tones when millions of grains are rubbed together by winds. The authors also discuss the effect of geologic phenomena on the sound and production of music—for instance, the acoustic qualities of music played in an auditorium built of stone.

Then there is the subject of musical compositions inspired by geoscientific or earth sciences phenomena. Among them are The Hebrides; or, Fingal's Cave by the German composer Felix Mendelssohn (1809-1847) as well as one the authors do not mention: The Planets, presented in 1918 by the German composer Gustav Holst (1874-1934). One also might list popular songs that refer to such phenomena, including "The White Cliffs of Dover." Written by Walter Kent and Nat Burton in 1941, the song epitomizes the longing for peace in a world torn by war. The cliffs themselves, which guard the eastern approaches of Britain, sometimes are referred to incorrectly as "chalk," though they are made of gypsum.

Ironically, rock music has few significant songs that refer to rocks. Usually the language is metaphoric, as was the case with the Bob Seger song discussed earlier. Hence, we have the name of the rock group Rolling Stones (with its implicit reference to the proverbial saying mentioned earlier) as well as the title to one of their earliest hits, "Heart of Stone." Jim Morrison's lyrics for the Doors include several references to the ground and things underneath it, including a gold mine in "The End." Coal mines have appeared in more than one song: "Working in the Coal Mine" was a hit for Lee Dorsey in the 1960s and was performed a new by the group Devo in 1981—not long after the Police song "Canary in a Coal Mine" appeared.

FILM.

More significantly, the year 1981 marked the release of Raiders of the Lost Ark, a film cited as a major turning point by Ted Nield in the Oxford Companion 's "Geoscience in the Media" entry. The film is not about a geoscientist but an archaeologist, Indiana Jones (played by the actor Harrison Ford); however, the character of Jones is based on an American paleontologist, Roy Chapman Andrews (1884-1960). Earlier movies, Nield observes, had portrayed the typical scientist as an "egghead …an arrogant, unworldly, megalomaniac obsessive …But with Indiana Jones we saw the beginning of a reaction. Increasing audience sophistication is part of the reason."

Nield goes on to discuss the movie Jurassic Park (1993), which features three scientists, all of whom receive positive treatment. The actor Sam Neill, as a paleontologist, is described as "dedicated—perhaps a bit too educated—but also intuitive, a superb communicator, and above all, knowledgeable about dinosaurs." Laura Dern, playing a paleobiologist, is "strong-willed, independent, feminist, and sexy," while Jeff Goldblum's mathematician is "weird, roguish, and cool." Sparking a widespread interest in dinosaurs and paleontology, the film (a major box-office hit directed by Steven Spielberg) helped advance the cause of the geosciences.

The positive trend in movie portrayals of geoscientists, Nield states, continued in Dante's Peak (1997), in which even the casting of the ultra-handsome actor Pierce Brosnan as a geologist says a great deal about changing perceptions of scientists. Noting that audiences had come to differentiate between science and the misapplication thereof, Nield observes that "The heat seems to have come off those who are merely curious about Nature's workings. "Additionally," by being associated with the open air and fieldwork, [geoscientists] can take on some of the clichéd but healthy characteristics usually associated on film with oilmen and lumberjacks."

In an entirely different category is another fascinating example of geoscience in film, Australian director Peter Weir's Picnic at Hanging Rock (1975). Weir, who went on to make such well-known films as The Year of Living Dangerously (1982), Witness (1985), and Dead Poets' Society (1989), established his reputation—and that of Australian cinema in general—with Picnic, which concerns the disappearance of a group of schoolgirls and their teacher on Valentine's Day, 1900. The story itself is fictional, though it seems otherwise (Picnic later inspired The Blair Witch Project, which also presents fiction as fact); however, the rock in the title is very much a real place. In the film, Hanging Rock is by far the most striking character, a brooding presence whose foreboding features serve as a reminder of Earth's vastness and great age in the face of human insignificance.

The Work of Geoscientists

The work of the geoscientist indeed is associated with the open air to a much greater degree than that of the physicist or chemist; on the other hand, a geoscientist might very well work indoors, for instance, as a teacher. Prospective geoscientists who subscribe to a worldview of environmental utopianism can get a job "saving the world"—perhaps even working for starvation wages, so as to heighten the nobility of the undertaking. On the other hand, a pragmatist can go to work for an "evil" oil company and make a good living. The point is that there is a little of something for everyone in the world of geoscience.

Geoscientists may work for educational institutions, governments, or private enterprise. They may be involved in the search for energy resources, such as coal or oil (or even uranium for nuclear power), or they may be put to work searching for valuable and precious metals ranging from iron to gold. They even may be employed in the mining of diamonds or other precious gems in South Africa, Russia, or other locales. Other, perhaps less glamorous but no less important resources for which geoscientists in various roles search are water as well as rocks, clay, and minerals for building.

The majority of employed geoscientists work for industry but not always in the capacity of resource extraction. Some are involved in environmental issues; indeed, environmental geology—the application of geologic techniques to analyze, monitor, and control the environmental impact of natural and human phenomena—is a growing field. Among the areas of concern for environmental geologists are water management, waste disposal, and land-use planning.

ENVIRONMENTAL AND URBAN GEOLOGY.

Many environmental geologists, as one might expect, are employed by governments. They may be involved in soil studies before the commencement of a building project, in analyzing the necessary thickness and materials for a particular stretch of road, or in designing and establishing specifications for a landfill. Many such concerns come into play when large populations gather together. In fact, a growing area of specialization in environmental geology is urban geology.

Urban geology can be defined as the application of geologic techniques to the study of the built environment. (The latter term is architectural and engineering jargon for any physical or geographic area containing human construction.) At first, "urban geology" might almost seem like an oxymoron, since the term geology usually calls to mind vast, unpopulated mountain ranges and rock formations—perhaps in South Dakota or Wyoming. In fact, geology is a major factor in the development of cities. Most are defined by their geomorphology: the hills of Athens and Rome, the mountains above Los Angeles, or the harbors of New York and other major ports, for instance.

Most cities have natural barriers to growth, and this is precisely because geomorphology originally dictated the location at which the city was established. A rare exception is Atlanta, Georgia, which grew around the point where several rail lines met. (In the 1840s, when it was established, it bore the name Terminus, a reference to the fact that it lay at the end of the rail line.) Bounded by no ocean, significant rivers, mountains, or other natural barriers, such as deserts, Atlanta began a period of explosive growth in the latter part of the twentieth century and has never stopped growing. Today Atlanta is a textbook example of urban sprawl: lacking a vital city center, it is a settlement of some four million people spread over an area much larger than Rhode Island, with no end to growth in sight.

Los Angeles often is cited as a case of urban sprawl, but its problems are quite different: it is rife with geomorphologic barriers, including oceans, mountains, and desert. The result is increasing growth within a limited area, resulting in heightened stress on existing resources. These are some of the issues confronted by urban geologists. Another example is the problem of determining the strength of bedrock, which dictates the viability of tall buildings. Urban geologists also are concerned with such issues as underground facilities for transportation, infrastructure, and even usable workspace—one possible solution to the problem of urban sprawl.

GEOARCHAEOLOGY AND RELATED FIELDS.

At the opposite extreme, in many ways, from urban geology is geoarchaeology, or the application of geologic analysis to archaeology and related fields. Whereas urban geology is concerned with the here and now, geoarchaeology—like the larger field of historical geology—addresses the past. And whereas urban geologists are most likely to be employed by governments, geoarchaeologists and those in similar areas are typically on the payroll of universities.

In a different sense, geoarchaeology also contrasts with archaeological geology, which is the study of archaeological sites for data relevant to the geosciences; thus, archaeological geology stands the approach of geoarchaeology on its head. An example of a study in archaeological geology can be found in the work conducted around the Roman ruins at Hierapolis in what is now Turkey. There, investigation of walls and gutters reveals the fact that the city was sitting astride an earthquake fault zone—a fact unknown to its residents, except when they experienced seismic tremors.

By contrast, an example of geoarchaeology in action would be establishing an explanation for how people came to the Americas from Siberia near the end of the last ice age—by crossing a land bridge that existed at that time. Another example of geoarchaeology would be the realm of ecclesiastical geology, which involves the study of old church masonry walls with the purpose of identifying areas from which rocks, bricks, and other materials were derived. Studies of medieval churches in England, for instance, show varieties of rock from sometimes unexpected locations, often placed alongside bricks taken from older Roman structures.

From the explanation and examples given here, it may be a bit hard to discern the difference between geoarchaeology and archaeological geology. Certainly there is a great deal of overlap, and in practice the difference comes down to a question of who is leading the fieldwork—a geologist or an archaeologist. In any case, both realms are concerned with the relatively recent human past, as opposed to the vast stretches of time that are the domain of historical geology (see Geologic Time).

FORENSIC GEOLOGY.

On October 7, 2001, the United States launched air strikes against Afghanistan in retaliation for the refusal of that country's Taliban regime to surrender Osama bin Laden, the suspected mastermind of the World Trade Center bombing on September 11. On the same day, bin Laden's al-Qaeda terrorist organization released a videotape of their leader delivering a diatribe against the United States. Naturally, military and law-enforcement agencies involved in the hunt for bin Laden took an interest in the tape, and some specialists sought clues in an unexpected place: the rocks behind bin Laden, featured prominently in the tape.

Although the efforts to trace bin Laden's location by the rock formations in the area were not successful, the underlying premise—that geographic regions have their own specific types and patterns of rock—was both a fascinating and a plausible one. This was just another example of a specialty known as forensic geology, or the use of geologic and other geoscientific data in solving crimes. Forensic geology has it origins around the beginning of the twentieth century, but some historians cite Sherlock Holmes, the master sleuth created by the English physician and writer Sir Arthur Conan Doyle (1859-1930), as an early practitioner.

In The Sign of Four, for instance, Holmes uses geologic data to ascertain that Watson has been to the Wigmore Street Post Office: "Observation tells me that you have a little reddish mould adhering to your instep," he explains. "Just opposite the Wigmore Street Office they have taken up the pavement and thrown up some earth, which lies in such a way that it is difficult to avoid treading in it in entering. The earth is of this peculiar reddish tint which is found, as far as I know, nowhere else in the neighbourhood."

The true founder of forensic geology was probably the Austrian jurist and pioneer in criminology Hans Gross (1847-1915), whose Handbuch für Untersuchungsrichter (Handbook for examining magistrates, 1898) was a pivotal work in the field. "Dirt on shoes," wrote Gross, "can often tell us more about where the wearer of those shoes has last been than toilsome inquiries." Near the turn of the nineteenth century, Germany's Georg Popp, who operated a forensic laboratory in Frankfurt, used the new science effectively in two cases.

The first of these cases involved the murder of a woman named Eva Disch in October 1904. Among the items found at the murder scene was a dirty handkerchief containing traces of coal, snuff, and hornblende, a mineral. Popp matched the handkerchief with a suspect who worked at two locations that used a great deal of horn-blende. In addition, the suspect's pants cuffs bore soil both from the murder scene and the victim's house.

Four years later, in investigating the murder of Margaethe Filbert in Bavaria, Popp ascertained that the soil at the crime scene was characterized by red quartz and red clay rich in iron. By contrast, the chief suspect had a farm whose fields were notable for their porphyry, milky quartz, and mica content. As it turned out, the suspect's shoes bore traces of quartz and red clay rather than those other minerals, even though he claimed he had been working in his fields when the crime occurred.

WHERE TO LEARN MORE

Career Information for Geology Majors (Web site). <http://www.uakron.edu/ascareer/Geology.html>.

Careers in the Geosciences (Web site). <http://www.agiweb.org/agi/careers.html>.

Geoarchaeology (Web site). <http://www.geoarchaeology.com/geoarc.htm>.

Geoarchaeology and Related Subjects (Web site). <http://archaeology.about.com/cs/earth sciences/>.

Geology in the City (Web site). <http://www.fortunecity.com/greenfield/ecolodge/60/cityhome.html>.

Hancock, Paul L., and Brian J. Skinner, eds. The Oxford Companion to the Earth. New York: Oxford University Press, 2000.

Murray, Raymond C. Devil in the Details: The Science of Forensic Geology (Web site). <http://www.forensicgeology.net/science.htm>.

Sarah Andrews Forensic Geology Pages (Web site). <http://www.sonoma.edu/Geology/andrews.htm>.

Sevil Atasoy's Links of Forensic Geology (Web site). <http://abone.turk.net/atasoy/forensicgeology.html>.

Urban Geology of the National Capital (Web site). <http://sts.gsc.nrcan.gc.ca/page1/urban/urb.htm>.

What Can I Do with a Degree in Geology? (Web site). <http://www.hartwick.edu/geology/alumni/careers.html>.

KEY TERMS

ATMOSPHERIC SCIENCES:

A major division of the earth sciences, distinguished from geoscience and the hydrologic sciences by its concentration on atmospheric phenomena. Among the atmospheric sciences are meteorology and climatology.

BIOSPHERE:

A combination of all living things on Earth—plants, mammals, birds, reptiles, amphibians, aquatic life, insects, viruses, single-cell organisms, and so on—as well as all formerly living things that have not yet decomposed.

EARTH SCIENCES:

The entire range of scientific disciplines focused on the study of Earth, including not only geoscience but also the atmospheric and hydrologic sciences.

ENVIRONMENTAL GEOLOGY:

A field of geology involved in the application of geologic techniques to analyze, monitor, and control environmental impact of both natural and human phenomena.

GEOCHEMISTRY:

A branch of the earth sciences, combining aspects of geology and chemistry, that is concerned with the chemical properties and processes of Earth—in particular, the abundance and interaction of chemical elements and their isotopes.

GEOLOGY:

The study of the solid earth, in particular, its rocks, minerals, fossils, and land formations.

GEOMORPHOLOGY:

An area of physical geology concerned with the study of landforms, with the forces and processes that have shaped them, and with the description and classification of various physical features on Earth.

GEOPHYSICS:

A branch of the earth sciences that combines aspects of geology and physics. Geophysics addresses the planet's physical processes as well as its gravitational, magnetic, and electric properties and the means by which energy is transmitted through its interior.

GEOSCIENCE:

The geologic sciences (geology, geochemistry, geophysics, and related disciplines), as opposed to other earth sciences—that is, atmospheric sciences, such as meteorology, and hydrologicsciences, such as oceanography.

GEOSPHERE:

The upper part of Earth's continental crust, or that portion of the solid earth on which human beings live and which provides them with most of their food and natural resources.

HISTORICAL GEOLOGY:

The study of Earth's physical history. Historical geology is one of two principal branches of geology, the other being physical geology.

HYDROLOGIC SCIENCES:

Areas of the earth sciences concerned with the study of the hydrosphere. Among these areas are hydrology, glaciology, and oceanography.

HYDROSPHERE:

The entirety of Earth's water, excluding water vapor in the atmosphere but including all oceans, lakes, streams, groundwater, snow, and ice.

ORGANIC:

At one time chemists used the term organic only in reference to living things. Now the word is applied to most compounds containing carbon, with the exception of carbonates (which are minerals) and oxides, such as carbon dioxide.

PHYSICAL GEOLOGY:

The study of the material components of Earth and of the forces that have shaped the planet. Physical geology is one of two principal branches of geology, the other being historical geology.

PHYSICAL SCIENCES:

Astronomy, physics, chemistry, and the earth sciences.

SEDIMENT:

Material deposited at or near Earth's surface from a number of sources, most notably preexisting rock. Soilis derived from sediment, particularly the mixture of rock fragments and organic material.