Earth science or geoscience includes all fields of natural science related to the planet Earth.
Geology
Geology is broadly the study of Earth's structure, substance, and processes. Geology is largely the study of the
lithosphere, or Earth's surface, including the crust and rocks. It includes the physical characteristics and processes that occur in the lithosphere as well as how they are affected by geothermal energy. It incorporates aspects of chemistry, physics, and biology as elements of geology interact. Historical geology is the application of geology to interpret Earth history and how it has changed over time.
Geochemistry studies the chemical components and processes of the Earth. Geophysics studies the physical properties of the Earth. Paleontology studies fossilized biological material in the lithosphere. Planetary geology studies geoscience as it pertains to extraterrestrial bodies. Geomorphology studies the origin of landscapes. Structural geology studies the deformation of rocks to produce mountains and lowlands. Resource geology studies how energy resources can be obtained from minerals. Environmental geology studies how pollution and contaminants affect soil and rock. Mineralogy is the study of minerals and includes the study of mineral formation, crystal structure, hazards associated with minerals, and the physical and chemical properties of minerals. Petrology is the study of rocks, including the formation and composition of rocks. Petrography is a branch of petrology that studies the typology and classification of rocks.
Earth's interior
Plate tectonics,
,
, and
are
geological phenomena that can be explained in terms of physical and chemical processes in the Earth's crust.
Beneath the Earth's crust lies the mantle which is heated by the radioactive decay of
heavy elements. The mantle is not quite solid and consists of
magma which is in a state of semi-perpetual . This convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics.
Areas of the crust where new crust is created are called
divergent boundaries, those where it is brought back into the Earth are
convergent boundaries and those where plates slide past each other, but no new lithospheric material is created or destroyed, are referred to as
transform fault (or conservative) boundaries.
result from the movement of the lithospheric plates, and they often occur near convergent boundaries where parts of the crust are forced into the earth as part of subduction.
Plate tectonics might be thought of as the process by which the Earth is resurfaced. As the result of seafloor spreading, new crust and lithosphere is created by the flow of magma from the mantle to the near surface, through fissures, where it cools and solidifies. Through subduction, oceanic crust and lithosphere vehemently returns to the convecting mantle.
Atmospheric science
Atmospheric science initially developed in the late-19th century as a means to forecast the weather through
meteorology, the study of weather. Atmospheric chemistry was developed in the 20th century to measure
air pollution and expanded in the 1970s in response to
acid rain.
Climatology studies the
climate and
climate change.
The troposphere, stratosphere, mesosphere, thermosphere, and exosphere are the five layers which make up Earth's atmosphere. 75% of the mass in the atmosphere is located within the troposphere, the lowest layer. In all, the atmosphere is made up of about 78.0% nitrogen, 20.9% oxygen, and 0.92% argon, and small amounts of other gases including CO2 and water vapor.
Earth's magnetic field
Hydrology
Hydrology is the study of the hydrosphere and the
Water cycle. It emphasizes the study of how humans use and interact with freshwater supplies. Study of water's movement is closely related to
geomorphology and other branches of Earth science. Applied hydrology involves engineering to maintain aquatic environments and distribute water supplies. Subdisciplines of hydrology include
oceanography,
hydrogeology,
ecohydrology, and
glaciology. Oceanography is the study of oceans.
Hydrogeology is the study of
groundwater. It includes the mapping of groundwater supplies and the analysis of groundwater contaminants. Applied hydrogeology seeks to prevent contamination of groundwater and
and make it available as
drinking water. The earliest exploitation of groundwater resources dates back to 3000 BC, and hydrogeology as a science was developed by hydrologists beginning in the 17th century.
Ecohydrology is the study of ecological systems in the
hydrosphere. It can be divided into the physical study of aquatic ecosystems and the biological study of aquatic organisms. Ecohydrology includes the effects that organisms and aquatic ecosystems have on one another as well as how these ecosystems are affected by humans.
Glaciology is the study of the cryosphere, including
and coverage of the Earth by ice and snow. Concerns of glaciology include access to glacial freshwater, mitigation of glacial hazards, obtaining resources that exist beneath frozen land, and addressing the effects of climate change on the cryosphere.
Ecology
Ecology is the study of the
biosphere. This includes the study of nature and of how living things interact with the Earth and one another and the consequences of that. It considers how living things use resources such as
oxygen,
water, and
from the Earth to sustain themselves. It also considers how humans and other living creatures cause changes to nature.
Physical geography
Physical geography is the study of Earth's systems and how they interact with one another as part of a single self-contained system. It incorporates astronomy, mathematical geography, meteorology, climatology, geology, geomorphology, biology, biogeography, pedology, and soils geography. Physical geography is distinct from
human geography, which studies the human populations on Earth, though it does include human effects on the environment.
Methodology
Methodology vary depending on the nature of the subjects being studied. Studies typically fall into one of three categories: observational, experimental, or theoretical. Earth scientists often conduct sophisticated computer analysis or visit an interesting location to study earth phenomena (e.g. Antarctica or hot spot island chains).
A foundational idea in Earth science is the notion of uniformitarianism, which states that "ancient geologic features are interpreted by understanding active processes that are readily observed." In other words, any geologic processes at work in the present have operated in the same ways throughout geologic time. This enables those who study Earth history to apply knowledge of how the Earth's processes operate in the present to gain insight into how the planet has evolved and changed throughout long history.
Earth's spheres
In Earth science, it is common to conceptualize the Earth's surface as consisting of several distinct layers, often referred to as spheres: the
lithosphere, the
hydrosphere, the
atmosphere, and the
biosphere, this concept of spheres is a useful tool for understanding the Earth's surface and its various processes
[ Earth's Spheres . ©1997–2000. Wheeling Jesuit University/NASA Classroom of the Future. Retrieved November 11, 2007.] these correspond to rocks,
water,
air and
life. Also included by some are the
cryosphere (corresponding to
ice) as a distinct portion of the hydrosphere and the
pedosphere (corresponding to
soil) as an active and intermixed sphere.
The following fields of science are generally categorized within the Earth sciences:
-
Geology describes the rocky parts of the Earth's crust (or lithosphere) and its historic development. Major subdisciplines are mineralogy and petrology, geomorphology, paleontology, stratigraphy, structural geology, engineering geology, and sedimentology.
-
Physical geography focuses on geography as an Earth science. Physical geography is the study of Earth's seasons, climate, atmosphere, soil, streams, landforms, and oceans. Physical geography can be divided into several branches or related fields, as follows: geomorphology, biogeography, environmental geography, palaeogeography, climatology, meteorology, coastal geography, hydrology, ecology, glaciology.
-
Geophysics and geodesy investigate the shape of the Earth, its reaction to forces and its magnetic field and . Geophysicists explore the Inner core and mantle as well as the Plate tectonics and Seismology activity of the lithosphere.
-
Geochemistry studies the processes that control the abundance, composition, and distribution of chemical compounds and isotopes in geologic environments. Geochemists use the tools and principles of chemistry to study the Earth's composition, structure, processes, and other physical aspects. Major subdisciplines are aqueous geochemistry, cosmochemistry, isotope geochemistry and biogeochemistry.
-
Soil science covers the outermost layer of the Earth's crust that is subject to soil formation processes (or pedosphere).
[ Elissa Levine, 2001, The Pedosphere As A Hub broken link?] Major subdivisions in this field of study include edaphology and pedology.
-
Ecology covers the interactions between organisms and their environment. This field of study differentiates the study of Earth from other planets in the Solar System, Earth being the only planet teeming with life.
-
Hydrology, oceanography and limnology are studies which focus on the movement, distribution, and quality of the water and involve all the components of the hydrologic cycle on the Earth and its atmosphere (or hydrosphere). "Sub-disciplines of hydrology include hydrometeorology, surface water hydrology, hydrogeology, watershed science, forest hydrology, and water chemistry."
-
Glaciology covers the ice parts of the Earth (or cryosphere).
-
Atmospheric sciences cover the parts of the Earth (or atmosphere) between the surface and the exosphere (about 1000 km). Major subdisciplines include meteorology, climatology, atmospheric chemistry, and atmospheric physics.
Earth science breakup
- Atmosphere
- Biosphere
- Hydrosphere
- Lithosphere (geosphere)
- Pedosphere
- Systems
- Others
See also
-
American Geosciences Institute
-
Earth sciences graphics software
-
Four traditions of geography
-
Glossary of geology terms
-
List of Earth scientists
-
List of geoscience organizations
-
List of unsolved problems in geoscience
-
Making North America
-
National Association of Geoscience Teachers
-
Solid-earth science
-
Science tourism
-
Structure of the Earth
Sources
Further reading
-
Allaby M., 2008. Dictionary of Earth Sciences, Oxford University Press,
-
Korvin G., 1998. Fractal Models in the Earth Sciences, Elsvier,
-
-
Tarbuck E. J., Lutgens F. K., and Tasa D., 2002. Earth Science, Prentice Hall,
External links
