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# Geophysics

Map of the age of the sea floor made from data about changes in the magnetic field.

Geophysics () is the physics of the Earth and its environment in space. It is also the study of the Earth by measuring things and collecting data. Sometimes geophysics means only studying the geology of the earth such as its shape, gravitational and magnetic field, internal structure and composition. It is can also mean how those create plate tectonics, magmas, volcanism and rock formation.[1]

Some geophysicists now also study the hydrological cycle including snow and ice. They study how the oceans and the atmosphere move. They study electricity and magnetism in the atmosphere, ionosphere, and magnetosphere. How the earth and sun affect each other is also part of geophysics.[1][2][3]

Geophysics was only recognized as a special area of study in the 19th century. But, there were geophysicists in ancient history. The first magnetic compasses were made in the fourth century BC and the first seismoscope was built in 132 BC. Isaac Newton applied his theory of mechanics to the tides and the precession of the equinox. Instruments were developed to measure the Earth's shape, density and gravity field, as well as parts of the water cycle. In the 20th century, geophysical methods were developed for remote exploration of the solid Earth and the ocean.

Studying geophysics may help with problems such as mineral resources, reducing natural hazards, and protecting the environment.[2] Geophysical survey data help find petroleum reservoirs, mineral deposits, groundwater, and archaeological relics. Such data can also tell the thickness of glaciers and soils, and tell which areas have environmental damage that should be fixed.

## References

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• Chemin, Jean-Yves; Desjardins, Benoit; Gallagher, Isabelle; Grenier, Emmanuel (2006). Mathematical geophysics: an introduction to rotating fluids and the Navier-Stokes equations. Oxford lecture series in mathematics and its applications. Oxford University Press.
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• Dewey, James; Byerly, Perry (1969). "The Early History of Seismometry (to 1900)". Bulletin of the Seismological Society of America 59 (1): 183–227.
• Defense Mapping Agency (1984) [1959]. "Geodesy for the Layman". National Geospatial-Intelligence Agency. (Technical report TR 80-003). Retrieved September 2011.
• Erastothenes (2010). Eratosthenes' "Geography". Fragments collected and translated, with commentary and additional material by Duane W. Roller. Princeton University Press.
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      . http://books.nap.edu/openbook.php?record_id=898&page=232.

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• Merrill, Ronald T.; McElhinny, Michael W.; McFadden, Phillip L. (1996). The Magnetic Field of the Earth: Paleomagnetism, the Core, and the Deep Mantle. International Geophysics Series. 63. Academic Press.
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• Muller, Paul; Sjogren, William (1968). "Mascons: lunar mass concentrations". Science 161 (3842): 680–684.
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• National Research Council (U.S.). Committee on Geodesy (1985) (book). Geodesy: a look to the future. National Academies.
• Newton, Isaac (1999). The Principia, Mathematical principles of natural philosophy. A new translation by I Bernard Cohen and Anne Whitman, preceded by "A Guide to Newton's Principia" by I Bernard Cohen. University of California Press.
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• Opdyke, Neil D.; Channell, James T. (1996). Magnetic Stratigraphy. Academic Press.
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• Pedlosky, Joseph (1987). Geophysical Fluid Dynamics (Second ed.). Springer-Verlag.
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• Poirier, Jean-Paul (2000). Introduction to the Physics of the Earth's Interior. Cambridge Topics in Mineral Physics & Chemistry. Cambridge University Press.
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     . http://anquetil.colorado.edu/EPP3/readings/Pollack_etal_1993_Rev_Geophys.pdf.

• Renne, P.R.; Ludwig, K.R.; Karner, D.B. (2000). "Progress and challenges in geochronology". Science Progress 83: 107–121.
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• Richards, M. A.; Duncan, R. A.; Courtillot, V. E. (1989). "Flood Basalts and Hot-Spot Tracks: Plume Heads and Tails". Science 246 (4926): 103–107.
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• Sadava, David; Heller, H. Craig; Hillis, David M.; Berenbaum, May (2009). Life: The Science of Biology. Macmillan.
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      . https://books.google.com/books?id=-nCHlVuJ4FoC&pg=PA286.

      . https://books.google.com/?id=yTsrAAAAYAAJ.