Earth Science Definitions

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earth science

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the scientific study of all aspects of Earth

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scientific method

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the way a scientist approaches a problem; steps include observing, formulating a hypothesis, testing, and evaluating results

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hypothesis

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a plausible, but yet to be proved, explanation for how something happens

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theory

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a hypothesis that has been tested and is strongly supported by experimentation, observation, and scientific evidence

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system

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a portion of the universe that can be separated from the rest of the universe for the purpose of observing changes that happen in it

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isolated system

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boundaries prevent the system from exchanging either matter or energy with its surroundings

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closed system

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boundaries that permit the exchange of energy, but not matter, with its surroundings (Earth)

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open system

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can exchange both matter and energy across its boundaries

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lithosphere

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open system where plants draw nutrients and where fossils are reentered

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geosphere

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collective interacting of the four open systems - lithosphere, biosphere, atmosphere, and hydrosphere

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life zone

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10 km above Earth's surface and 10 km below where four systems interact most intensively

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feedback mechanisms

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reactions that enhance (positive) or retard (negative) change in an open system

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earth system science

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the study of Earth as a closed system composed of interacting open systems and hwo the open systems may be changed as a result of human activities

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chemical differentiation

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separation into layers of different composition (silica outwards, iron inwards)

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core

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Earth's innermost compositional layer, where the magnetic field is generated and much geothermal energy resides

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mantle

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the middle compositional layer between the crust and the core

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crust

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outermost compositional layer of the solid Earth; part of the lithosphere

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crust and mantle divided into what three layers?

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lithosphere, asthenosphere, mesophere

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lithosphere

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Earth's outermost rocky layer, comprising the crust and the uppermost part of the mantle

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asthenosphere

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a layer of weak, ductile rock in the mantle that is close to melting but not actually molten

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weathering

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chemical alteration and mechanical breakdown of rock caused by exposure to water, air, and living organisms

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regolith

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layer of irregular blanket of loose debris formed as a result of weathering - soil, river mud, desert sand, rock fragments, unconsolidated debris

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soil

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when material from the biosphere becomes incorporated with rock material

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plate tectonics

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the movement and interactions of large fragments of Earth's lithosphere, called plates

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oceanic crust

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the thinner, denser, and younger part of Earth's crust, underlying the ocean basins - characterized by common volcanic rock, basalt

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continental crust

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the older, thicker and less dense part of Earth's crust; the bulk of Earth's land masses - igneous rock, granite

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natural resources

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useful materials obtained from the lithosphere, atmosphere, hydrosphere, or biosphere

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mineral

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-be a naturally occuring solid
-be formed by inorganic processes
-have a characteristi crystal structure
-have a specific chemical composition

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rock

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solid aggregate of minerals

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element

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the most fundamental substance into which matter can be separated by chemical means

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atom

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the smallest individual particle that retains the distinctive chemical properties of an element

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atomic number

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number of protons in an atom

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mass number

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number of protons plus number of neutrons in the nucleus

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isotopes

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atoms with the same atomic number and different mass numbers

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ion

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atom that gains or loses electrons

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cation

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atom that loses electrons

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anion

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atom that gains electrons

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compound

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combination of atoms of one or more elements in a specific ratio

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molecule

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smallest chemical unit that has all the properties of a particular compound

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bonds

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force that holds atoms together in a chemical compound