chapter 2

Mesosphere

(1) (geosphere) the division of the mantle between the asthenosphere and the outer core. (2) (atmosphere) the division of the atmosphere above the stratosphere that begins about 50 km (31 miles) in altitude and extents to above 80 km (50 miles)

Convection

(1) (physics) heat transfer in a gas or liquid by the circulation of currents from one region to another; also fluid motion caused by an external force such as gravity. (2) (meteorology) the phenomenon occurring where large masses of warm air, heated by contact with a warm land surface and usually containing appreciable amounts of moisture, rise upward form the surface of the earth

Asthenosphere

* The uppermost layer of the mantle, located below the lithosphere. This zone of soft (plastic), easily deformed rock exists at depths of 100 km to as deep as 700 km

Divergent Plate Boundary

A boundary in which two lithospheric (tectonic) plates move apart

Convergent Plate Boundary

A boundary in which two plates collide. The collision can be between two continents (continental collision), a relatively dense oceanic plate and a more buoyant continental plate (subduction zone) or two oceanic plates (subduction zone)

Ecosystem

A community of plants, animals and other organisms that interact together within their given setting

Rock

A naturally occurring aggregate of minerals. Rocks are classified by mineral and chemical composition; the texture of the constituent particles; and also by the processes that formed them. Rocks are thus separated into igneous, sedimentary, and metamorphic rocks

Weathering

A process that includes two surface or near-surface processes that work in concert to decompose rocks. Chemical weathering involves a chemical change in at least some off the minerals within a rock. Mechanical weathering involves physically breaking rocks into fragments without changing the chemical make-up of the minerals within in

Igneous Rock

A rock formed when molten rock (magma) has cooled and solidified (crystallized). Igneous rocks can be intrusive (plutonic) and extrusive (volcanic).

Metamorphic Rock

A rock that has been altered physically, chemically, and mineralogically in response to strong changes in temperature, pressure, shearing stress, or by chemical action of fluids

Sedimentary Rock

A sedimentary rock is formed from pre-existing rocks or pieces of once living organisms. The form from deposits that accumulate on the Earth's surface. Sedimentary rocks often have distinctive layering or bedding

Transform Fault

A strike-slip fault with side to side horizontal movement that offsets segments of an oceanic ridge

Plate Boundary

According to the theory of plate tectonics, the locations where the rigid plates that comprise the crust of the earth meet. As the plates meet, the boundaries can be classified as: divergent (places where the plates are moving apart, as the mid-ocean ridges of the Atlantic Ocean) convergent (places where the plates are colliding, as at the Himalayas Mountains) transform (places where the plates are sliding past each other, as the San Andreas fault in California)

Carbon Cycle

All carbon reservoirs and exchanges or carbon from reservoir by various chemical, physical, geological, and biological processes. Usually thought of as a series of the four main reservoirs of carbon interconnected by pathways of exchange. The four reservoirs, regions of the earth in which carbon behaves in a systematic manner, are the atmosphere, terrestrial biosphere (usually includes fresh water systems), oceans, and sediments (includes fossil fuels). Each of these global reservoirs may be subdivided into smaller pools, ranging in size from individual communities or ecosystems to the total of all living organisms (biota).

Subduction Zone

Also called a convergent plate boundary. And area where two plates meet and one is puled beneath the other

Island Arc

An arc-shaped chain of volcanic islands produced where an oceanic plate is sinking (subducting) beneath another

Transform Plate Boundary

An area where two plates meet and are moving side to side past each other

Oceanic Ridge

An uplifting of the ocean floor that occurs when convection currents beneath the ocean bed force magma up where two tectonic places meet at a divergent boundary. The ocean ridges of the world are connected and forms a single global ridge system that is part of every ocean and form the longest mountain range on Earth.

Mineral

Any naturally occurring inorganic substance found in the earth's crust as a crystalline solid

Volcanic Arc

Arcuate chain of volcanoes formed above a subducting plate. The arc forms where the downgoing descending plate becomes hot enough to release water and gases that rise into the overlying mantle and cause it to melt

Impact Energy

Cosmic impacts with a larger body convert their energy of motion (kinetic energy) to heat

Oceanic Trench

Deep, linear, steep-sided depression on the ocean floor caused by the subduction of oceanic crustal plate beneath either other oceanic or continental crustal plates

Radiation

Energy emitted in the form of electromagnetic waves. Radiation has differing characteristics depending upon the wavelength. Because the radiation from the Sun is relatively energetic, it has a short wavelength (ultra-violet, visible, and near infrared) while energy radiated from the Earth's surface and the atmosphere has a longer wavelength (e.g., infrared radiation) because the Earth is cooler than the Sun

Heat Transfer

Heat moving from a hot body to a cold one through processes of conduction, convection, or radiation, or any combination of these

Conduction

Heat transfer directly from atom to atom in solids

Radioactive Decay

Natural spontaneous decay of the nucleus of an atom where alpha or beta and/or gamma rays are released at a fixed rate

Subduction

Process of one crustal plate sliding down and below another crustal plate as the two converge

Potential Energy

The energy available in a substance because of position (e.g., water held behind a dam) or chemical composition (hydrocarbons). This form of energy can be converted to other, more useful forms (for example, hydroelectric energy from falling water)

Kinetic Energy

The energy inherent in a substance because of its motion, expressed as a function of its velocity and mass, or MV2/2

Gravitational Energy

The force of attraction between objects due to their mass and is produced when an object falls from higher to lower elevations

plate tectonics

The theory that the earth's lithosphere consists of large, rigid plates that move horizontally in response to the flow of the asthenosphere beneath them, and that interactions among the plates at their borders (boundaries) cause most major geologic activity, including the creation of oceans, continents, mountains, volcanoes, and earthquakes.

Convection Cell

Within the geosphere it is the movement of the asthenosphere where heated material from close to the Earth's core becomes less dense and rises toward the solid lithosphere. At the lithosphere-asthenosphere boundary heated asthenosphere material begins to move horizontally until it cools and eventually sinks down lower into the mantle, where it is heated and rises up again, repeating the cycle

Lithospheric Plate

a series or rigid slabs of lithosphere (12 majors ones at present) that make up the earth's outer shell. These plates float on top of a softer, more plastic layer in the earth's mantle known as the asthenosphere

Earth System

composed of the geosphere, hydrosphere, atmosphere, and biosphere, and all of their components, continuously interacting as a whole

Biogeochemical Cycle

natural processes that recycle nutrients in various chemical forms from the environment, to organisms, and then back to the environment. Examples are the carbon, oxygen, nitrogen, phosphorous, and hydrologic cycles

Silicate

refers to the chemical unit silicon tetrahedron, SiO4, the fundamental building block of silicate minerals. Silicate minerals represent about 1/3 of all minerals and hence make up most rocks we see at the Earth's surface

Plate

slab of rigid lithosphere (crust and uppermost mantle) that moves over the asthenosphere

Oceanic Crust

that part of the earth's crust of the geosphere underlying the ocean basins. It is composed of basalt and has a thickness of about 5 km

Atmosphere

the air surrounding the earth, from sea level to outer space

Hydrologic Cycle

the cyclic transfer of water in the hydrosphere by water movement from the oceans to the atmosphere and to the Earth and return to the atmosphere through various stages or processes such as precipitation, interception, runoff, infiltration, percolation, storage, evaporation, and transportation

Core

the innermost layer of the Earth, made up of mostly of iron and nickel. The core is divided into a liquid outer core and a solid inner core. The core is the densest of the Earth's layers

Mantle

the layer of the earth below the crust and above the core. The uppermost part of the mantle is rigid and, along with the crust, forms the 'plates' of the plate tectonics. The mantle is made up of dense iron and magnesium rich (ultramafic) rock such as peridotite.

Stratosphere

the level of the atmosphere above the troposphere, extending to about 50-55 kilometers above Earth's surface

Outer Core

the liquid outer layer of the core that lies directly beneath the mantle

Biosphere

the living and dead organisms found near the earth's surface in parts of the lithosphere, atmosphere, and hydrosphere. The part of the global carbon cycle that includes organism and biogenic organic matter

Troposphere

the lowest part of the atmosphere that is in contact with the surface of the Earth. It ranges in altitude above the surface up to 10 or 12 kilometers

Lithosphere

the outer layer of solid rock that includes the crust and upper most mantle. This layer, up to 100 km (60 miles) thick, forms the earth's tectonic plates. Tectonic plates float above the more dense, flowing layer of mantle called the asthenosphere.

Hydrosphere

the part of the Earth composed of water including clouds, oceans, seas, ice caps, glaciers, lakes, rivers, underground water supplies, and atmospheric water vapor

Crust

the rocky, relatively low density, outer most layer of the Earth

Rock Cycle

the sequence of events in which rocks are formed, destroyed, and reformed by geological processes. Provides a way of viewing the interrelationship of internal and external processes and how the three rock groups relate to each other

Geosphere

the soils, sediments, and rock layers of the earth including the crust, both continental, and beneath the ocean floors

Inner Core

the solid central part of earth's core