Portal:Earth sciences

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Introduction

Earth sciences (also known as geoscience, the geosciences or Earth Science) is an all-embracing term for the sciences related to the planet Earth. It is a special type of planetary science which deals with the structure and composition of the Earth, its origins, physical features, changing aspects, and all of its natural phenomena.

The major disciplines of the Earth sciences use physics, mathematics, and chemistry to build a quantitative understanding of the principal areas or spheres of the Earth system. Like in many sciences, the Earth can be studied both experimentally and theoretically. Also, there are both reductionist and holistic approaches to Earth Science.

Although mining and precious stones have been human interests throughout the history of civilization, their development into the sciences of economic geology and mineralogy did not occur until the 18th century. The study of the earth, particularly palaeontology, blossomed in the 19th century and the growth of other disciplines like geophysics in the 20th century led to the development of the theory of plate tectonics in the 1960s, which has had a similar impact on the Earth sciences as the theory of evolution had on biology. Earth sciences today are closely linked to climate research and the petroleum and mineral exploration industries.

Applications of the Earth sciences include the exploration and exploitation of mineral and hydrocarbon resources, cartography, weather forecasting patterns, and warning of volcanic eruptions. The Earth sciences are related to the environmental sciences as well as the other subfields of planetary astronomy.

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Plate tectonics is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere. The theory encompassed and superseded the older theory of continental drift from the first half of the 20th century and the concept of seafloor spreading developed during the 1960s. The outermost part of the Earth's interior is made up of two layers: above is the lithosphere, comprising the crust and the rigid uppermost part of the mantle. Below the lithosphere lies the asthenosphere. Although solid, the asthenosphere has relatively low viscosity and shear strength and can flow like a liquid on geological time scales. The deeper mantle below the asthenosphere is more rigid again. This is, however, not due to cooler temperatures but due to high pressure. The lithosphere is broken up into what are called tectonic plates—in the case of Earth, there are seven major and many minor plates (see list below). The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent or collision boundaries, divergent or spreading boundaries, and transform boundaries. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The lateral movement of the plates is typically at speeds of 0.65 to 8.50 centimeters per year (the speed at which human nails grow).
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Full Moon partially obscured by the atmosphere of Earth.
Credit: NASA

Astronauts aboard the Space Shuttle Discovery recorded this rarely seen phenomenon of the full Moon partially obscured by the atmosphere of Earth. The image was recorded with an electronic still camera at 15:15:15 GMT, Dec. 21, 1999

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Did you know?

  • ...that a tuya (as pictured) is a type of flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet?
  • ...that in the United States, on average tornadoes are around 500 feet (150 m) across, and stay on the ground for 5 miles (8 km)?
  • ...that dust storms can carry large amounts of dust, so much so that the leading edge of one can appear as a solid wall of dust as much as 1.6 km (1 mile) high?
  • ...that the area of the world Ocean is 361 million square kilometers, its volume is approximately 1.3 billion cubic kilometers, and its average depth is 3,790 meters?
  • ...that three quarters of the earth's atmosphere lies within the troposphere, and the depth of this layer varies between 17 km at the equator and 7 km at the poles?
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