Everything about Earth Science totally explained
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 science. There are four major
disciplines in earth sciences, namely
geography,
geology,
geophysics and
geodesy. The major
disciplines use
physics,
chemistry,
biology and
mathematics to build a quantitative understanding of the principal areas or
spheres of the Earth system.
Earth's spheres
Earth science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere. These correspond to rocks, water, air, and life. Some practitioners include the cryosphere (ice) as a distinct portion of the hydrosphere and the pedosphere (soil) as an active, intermixed sphere as part of Earth's spheres.
- Geology describes the rocky parts of the Earth's crust (or lithosphere) and its historic development. Major subdisciplines are mineralogy and petrology, geochemistry, geomorphology, paleontology, stratigraphy, structural geology, engineering geology and sedimentology.
- Geophysics and Geodesy investigate the figure of the Earth, its reaction to forces and its magnetic and gravity fields. Geophysicists explore the Earth's core and mantle as well as the tectonic and seismic activity of the lithosphere.
- Soil science covers the outermost layer of the Earth's crust that's subject to soil formation processes (or pedosphere). Major subdisciplines include edaphology and pedology.
- Oceanography and hydrology (includes limnology) describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere). Major subdisciplines include hydrogeology and physical, chemical, and biological oceanography.
- Glaciology covers the icy parts of the Earth (or cryosphere).
- Atmospheric sciences cover the gaseous parts of the Earth (or atmosphere) between the surface and the exosphere (~1000 km). Major subdisciplines are meteorology, climatology, atmospheric chemistry and atmospheric physics.
- A very important linking sphere is the biosphere, the study of which is biology. The biosphere consists of all forms of life, from single-celled organisms to pine trees to people. The interactions of Earth's other spheres - lithosphere/geosphere, hydrosphere, atmosphere and/or cryosphere and pedosphere - create the conditions that can support life.
Earth's interior
Plate tectonics,
mountain ranges,
volcanoes, and
earthquakes are
geological phenomena that can be explained in terms of
energy transformations 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 isn't 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.
Plate tectonics might be thought of as the process by which the earth resurfaces itself. Through a process called
spreading ridges (or
seafloor spreading), the earth creates new crust by allowing magma underneath the lithosphere to come to the surface where it cools and solidifies--becoming new crust, and through a process called
subduction, excess crust is pushed underground--beneath the rest of the lithosphere--where it comes into contact with magma and melts--rejoining the mantle from which it originally came.
Areas of the crust where new crust is created are called
divergent boundaries, and areas of the crust where it's brought back into the earth are called
convergent boundaries.
Earthquakes result from the movement of the lithospheric plates, and they often occur near covergent boundaries where parts of the crust are forced into the earth as part of subduction.
Volcanoes result primarily from the melting of subducted crust material. Crust material that's forced into the
Asthenosphere melts, and some portion of the melted material becomes light enough to rise to the surface--giving birth to volcanoes. The earth has a soft iron
core surrounded by semi-liquid materials from the mantle that move in continuous currents around the core; therefore, the earth is an . This is referred to as the
dynamo theory of earth's magnetism. The fact that earth is an electromagnet helps with the earth's maintenance of an atmosphere suitable for life.
Atmosphere
The earth is blanketed by an
atmosphere consisting of 78.0% nitrogen, 20.9% oxygen, and 1% Argon. The atmosphere has five layers:
troposphere,
stratosphere,
mesosphere,
thermosphere, and
exosphere; and 75% of the atmosphere's gasses are in the bottom-most layer, the troposphere. It is theorized that the solar wind would strip away earth's atmosphere in a few million years were it not for the earth's electromagnet. And since earth is
4.5 billion years old, earth wouldn't have an atmosphere by now if there were no magnetosphere.
The atmosphere is composed of 78%
nitrogen and 21%
oxygen. The remaining one percent contains small amounts of other gasses including CO
2 and water vapors. This allows earth's surface to be warm enough to have liquid water and support life.
In addition to storing heat, the atmosphere also protects living organisms by shielding the earth's surface from
cosmic rays. Note that the level of protection is high enough to prevent cosmic rays from destroying all life on Earth, yet low enough to aid the
mutations that have an important role in pushing forward
diversity in the biosphere.
Methodology
Like all other scientists, Earth scientists apply the
scientific method. They formulate
hypotheses after observing events and gathering data about natural phenomena, and then they test those hypotheses. In Earth science, data usually plays a major role in testing and formulating hypotheses.
A driving philosophical force behind contemporary earth science is
uniformitarianism. Uniformitarianism says that "ancient geologic features are interpreted by understanding active processes that are readily observed".
Simply stated, this means that dramatic and awe-inspiring features of the earth can be explained by the actions of gradual processes operating over long periods of time; for example, a mountain need not be thought of as having been created in a moment, but instead it may be seen as the result of earthquake after earthquake raising the ground in a certain area by small amounts over millions of years.
Partial list of the major Earth Science topics
Atmosphere
Atmospheric chemistry
Climatology
Meteorology
Paleoclimatology
Biosphere
Biogeography
Paleontology
Geomicrobiology
Hydrosphere
Hydrology
Hydrogeology
Oceanography
Lithosphere or geosphere
Geology
Geochemistry
Geography
Geomorphology
Geophysics
Hydrogeology
Mineralogy
Petrology
Volcanology
Pedosphere
Soil science
Systems
Environmental science
Geography
Gaia hypothesis
Others
Cartography
Geoinformatics (GIS)
Geostatistics
Geodesy and Surveying
NASA Earth Science Enterprise
Notes and references
Further Information
Get more info on 'Earth Science'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://earth_science.totallyexplained.com">Earth science Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
