Geoscience Chapter 1

Geology

The study of Earth, including its physical processes and history.

Physical Geology

The study of Earth's internal and external processes.

Historical Geology

The study of Earth's origin, evolution through geologic time, and life on Earth.

Internal Processes

Processes occurring within Earth that build and deform Earth's surface.

External Processes

Processes occurring at Earth's surface that break down and reshape it.

Weathering

The breakdown of Earth materials at the surface.

Erosion

The removal and movement of weathered material.

Transport

The movement of sediment or weathered material.

Deposition

The process by which transported sediment is laid down.

Mass Wasting

The movement of Earth materials downslope due to gravity.

Renewable Resource

A resource that can be replenished over relatively short periods of time.

Nonrenewable Resource

A resource that cannot be replenished except over geologic time.

Economic Geology

The study of Earth's natural resources needed for modern civilization.

Natural Resources

Materials from Earth that humans use, including oil, gas, minerals, water, and soil.

Ga (Giga-annum)

A unit representing one billion years ago in geologic and scientific time.

Geologic Time Scale

Earth's history divided into large and smaller blocks of geologic time.

Eon

A large division of geologic time lasting hundreds to thousands of millions of years.

Era

A subdivision of an eon.

Period

A subdivision of an era.

Epoch

A subdivision of a period.

Cambrian Explosion

A period of rapid diversification of life following the appearance of hard shells around 542 Ma.

Great Oxidation Event

A major increase in atmospheric oxygen around 2.4 Ga caused by photosynthetic microorganisms.

Catastrophism

The belief that Earth's landscapes were formed by great catastrophes.

Big Bang

The event in which all mass and energy were concentrated in a single point and the universe began expanding.

Matter

The substance of the universe that takes up space.

Energy

The ability to do work.

Doppler Effect

The change in observed wavelength or frequency caused by relative motion between a source and observer.

Redshift

The shift of light toward longer wavelengths when an object moves away from an observer.

Blueshift

The shift of light toward shorter wavelengths when an object moves toward an observer.

Galaxy

A vast system of stars bound together by gravity.

Milky Way

The galaxy containing our Solar System.

Terrestrial Planets

Small, dense, rocky planets: Mercury, Venus, Earth, and Mars.

Giant Planets

Large, low-density gas and ice giants.

Gas Giants

Jupiter and Saturn, composed mainly of hydrogen and helium.

Ice Giants

Uranus and Neptune, containing frozen water, ammonia, and methane.

Planetesimal

A small body that can clump together with others to form a protoplanet.

Differentiation

The process in which Earth separates into layers based on density, producing an iron-rich core and stony mantle.

System

A portion of the universe that can be isolated from the rest for observing and measuring change.

Isolated System

A system whose boundary prevents the exchange of both matter and energy.

Open System

A system that can exchange both matter and energy across its boundary.

Closed System

A system that exchanges energy with its surroundings but not matter.

Earth System

The communicating components of Earth: atmosphere, geosphere, hydrosphere, biosphere, and cryosphere.

Atmosphere

The gaseous part of Earth.

Geosphere

The solid Earth, including rocks, soil, and continents.

Hydrosphere

All bodies of water on Earth.

Biosphere

All living organisms on Earth.

Cryosphere

The ice in Earth's polar regions.

Hydrologic Cycle

The movement of water through evaporation, atmosphere, precipitation, runoff, infiltration, and back to the ocean.

Topography

The variations in land elevation that create features such as plains, mountains, and valleys.

Bathymetry

The variations in elevation and depth of the seafloor.

Sediment

An accumulation of loose mineral grains produced by weathering, erosion, or precipitation.

Magma

Molten rock beneath Earth's surface.

Lava

Molten rock at Earth's surface.

Volatiles

Materials that turn into gas at Earth's surface, such as H2O, CO2, and SO2.

Silicate

A mineral or material based on silicon and oxygen.

Igneous Rock

Rock that forms when a melt cools.

Sedimentary Rock

Rock formed from debris cemented from preexisting rock.

Metamorphic Rock

Rock altered by pressure and temperature.

Metal

A solid composed of metal atoms that generally has high density, is shiny, and conducts electricity.

Alloy

A material containing a metal combined with another element.

Crust

The thin, rocky outer layer of Earth.

Mantle

The thick layer of solid rock beneath the crust.

Core

The innermost, very dense, iron-rich layer of Earth.

Continental Crust

Crust underlying continents; relatively thick, felsic to intermediate, and less dense.

Oceanic Crust

Crust underlying ocean basins; thinner, mafic, and denser than continental crust.

Mohorovičić Discontinuity (Moho)

The boundary between Earth's crust and mantle.

Seismic Waves

Waves of seismic energy produced by earthquakes that provide information about Earth's interior.

Mantle Convection

The movement in the mantle in which hot material rises and cooler material sinks.

Outer Core

The liquid portion of Earth's iron-rich core.

Inner Core

The solid portion of Earth's iron-rich core.