(also known as geoscience
, the geosciences
or Earth Science
) is an all-embracing term for the sciences
related to the planet Earth
. They are a special type of planetary sciences
which deal with the structure and composition of the Earth, its origins, physical features, changing aspects, and all of its natural phenomena. Earth is the only planet known to have life, and hence the only planet with biological processes and a biosphere.
The major disciplines of Earth sciences use physics, mathematics, and chemistry to build a quantitative understanding of the principal areas or spheres of the Earth system. As 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 in 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 Earth sciences include the exploration and exploitation of mineral and hydrocarbon resources, cartography, weather forecasting patterns, and warning of volcanic eruptions. Earth sciences are related to the environmental sciences as well as the other subfields of planetary astronomy.
is a volcanic, tectonically
unstable island in the Rat Islands
group of the Aleutian Islands
in southwest Alaska
. It is about 68 kilometres (42 mi) long, and varies from 3 to 6 km (2–3.75 mi) in width. It has a maritime climate, with many storms, and mostly overcast skies. The island was populated for more than 2,500 years by the Aleut
people, but has had no permanent population since 1832. It was included in the Alaska Purchase
of 1867, and has since been part of the United States
. During World War II
, it was used as an airfield by US forces in the Battle of the Aleutian Islands
. Amchitka was selected by the United States Atomic Energy Commission
to be the site for underground detonations
of nuclear weapons
. Three such tests were carried out: Long Shot
, an 80 kiloton
blast in 1965; Milrow
, a 1 megaton
blast in 1969; and Cannikin
in 1971 — at "under 5 megatons", the largest underground test
ever conducted by the United States. The tests were highly controversial, with environmental groups
fearing that the Cannikin
explosion, in particular, would cause severe earthquakes
. Amchitka is no longer used for nuclear testing, although it is monitored for the leakage of radioactive materials