The lowest layer of soil; partially altered bedrock.
caldera
Circular-shaped hole into which a volcano collapses during an eruption.
cap-and-trade
A monetary system that encourages conservation and development of alternative energy sources. A cap is put on a nation’s allowed carbon emissions and nations can trade for rights to emit carbon pollution.
capillary action
Water moves from wet to dry regions in soil.
carbohydrate
Organic compound that supplies energy to the body; includes sugars, starches and cellulose.
carbon sequestration
Removal of carbon dioxide from the atmosphere, so that it does not act as a greenhouse gas in the atmosphere.
carbon sink
A reservoir for carbon that absorbs more carbon dioxide than it produces.
carbon source
An area of an ecosystem that emits more carbon dioxide than it absorbs.
carbon tax
A tax placed on energy sources that emit carbon to discourage their use and to raise funds to research alternative energy sources.
carnivore
Animals that only eat other animals for food.
carrying capacity
The number of individuals of a given species a particular environment can support.
cast
A mold filled with sediment and hardened to create a replica of the original fossil.
catadioptric telescope
Telescopes that use a combination of mirrors and lenses to focus light.
catalyst
A substance that increases (or decreases) the rate of a chemical reaction but is not used up in the reaction.
catalytic converter
Found on modern motor vehicles, these devices use a catalyst to break apart pollutants.
cementation
When fluids deposit ions to create a cement that hardens loose sediments.
chaparral
Scrubby woody plants and widely scattered trees typical of the Mediterranean climate.
chemical bond
The force that holds two atoms together.
chemical compound
A substance in which the atoms of two or more elements bond together.
chemical energy
Energy that is stored in the chemical bonds in molecules.
chemical sedimentary rocks
Rocks that form from the hardening of chemical precipitates.
chemical weathering
Weathering that changes the chemical composition of minerals that form at high temperatures and pressures to minerals that are stable at the Earth’s surface.
chemosynthesis
The breakdown of chemicals to produce food energy.
Chinook winds (Foehn winds)
Winds that form when low pressure draws air over a mountain range.
chromosphere
Thin layer of the Sun’s atmosphere that lies directly above the photosphere; glows red.
cinder cone
A small volcano composed of small rock fragments piled on top of one another.
clastic
Fragments or clasts of preexisting rock; a sedimentary rock made of clasts.
cleavage
The tendency of a mineral to break along certain planes to make smooth surfaces.
climate
The long-term average of weather.
cloud
Tiny water or ice particles that are grouped together in the atmosphere.
coal
A solid fossil fuel from ancient dead organisms used for electricity.
cold front
A front in which a cold air mass pushes a warm air mass upward.
column
A cave deposit formed by the merging of a stalactite and a stalagmite.
comet
A small, icy, dusty object with a bright tail in orbit around the Sun.
commensalism
A relationship in which one species benefits and the other species is not harmed.
community
All of the populations of organisms in an ecosystem.
compaction
When sediments are squeezed together by the weight of sediments and rocks on top of them.
compass
Hand-held device with a magnetic needle used to find magnetic north.
compass rose
Figure on a map or nautical chart for displaying locations of north, south, east, and west.
competence
A measure of the largest particle a stream can carry.
competition
A rivalry between two species, or individuals of the same species, for the same resources.
composite volcano
A large, steep-sided composed of alternating layers of ash and lava flows.
compression
Stresses that push toward each other, causing a decrease in the space a rock takes up.
conceptual model
An abstract, mental representation of an object or system.
condensation
The change in a substance from a gas to a liquid, releases energy.
conduction
The process in which energy moves from a location of higher temperature to a location of lower temperature as heat. The material does not move, just the heat.
confining stress
Stress from the weight of material above a buried object; reduces volume.
confluence
Where two streams join together.
conserve
To reduce the use of a natural resource so that it will last longer.
constellation
A group of stars that appear to form a pattern in the sky. Most often these stars are unrelated and are not near each other in space. Constellations are used to locate objects in space.
constructive forces
Forces that cause landforms to grow. Crustal deformation and volcanic eruptions are two examples.
consumer
An organism that uses other organisms for food energy.
consumptive water use
Water use in which the water is lost to the ecosystem.
contact metamorphism
Changes in a rock that result from temperature increases when a body of magma contacts a cooler existing rock.
continent
Land mass above sea level.
continental arc
A line of volcanoes on a continent resulting from subduction beneath the continent.
continental climate
A more variable climate dominated by a vast expanse of land.
continental crust
The crust that makes up the continents; thicker and less dense than oceanic crust.
continental divide
A divide that separates water that goes to different oceans.
continental drift
The early 20th century hypothesis that the continents move about on Earth’s surface.
continental glacier
A sheet of ice covering a large area that is not confined to a valley.
continental margin
Submerged, outer edge of the continent. It is the transition zone from land to deep sea where continental crust gives way to oceanic crust.
continental rifting
A divergent plate boundary that breaks up a continent.
contour interval
The constant difference in elevation between two contour lines on a topographic map.
contour line
A line on a topographic map to show elevation.
control
Factors that are kept the same in an experiment so that only the independent variable is tested.
convection
The movement of material due to differences in temperature.
convection cell
A circular pattern of warm material rising and cool material sinking.
convection zone
Layer of the Sun that surrounds the radiative zone where energy moves as flowing cells of gas.
convergent plate boundary
A location where two lithospheric plates come together.
core
The innermost, densest layer of a celestial body. Earth’s metallic core has an inner solid layer and an outer layer of liquid metal. The sun’s core is where nuclear fusion takes place.
Coriolis effect
The apparent deflection of a freely moving object like water or air because of Earth’s rotation.
corona
Outermost layer of the Sun; a plasma that extends millions of kilometers into space.
cosmology
The study of the universe.
covalent bond
Electrons shared between atoms.
crater
Bowl-shaped depressions on the surface of the Moon caused by impact from meteorites.
craton
The ancient Precambrian felsic continental crust that forms the cores of continents.
creep
Exceptionally slow movement of soil downhill.
crescent
Phase of the moon when it is less than half full but still slightly lit.
crest
The highest point of a wave.
cross-cutting relationships
One of Steno’s principles that states that an intrusion or fault is younger than the rocks that it cuts through.
crude oil
Unrefined oil as it is taken from the ground; a fossil fuel.
crust
The rocky outer layer of the Earth’s surface. The two types of crust are continental and oceanic.
crystal
A solid in which all the atoms are arranged in a regular, repeating pattern.
crystallization
The formation of mineral grains from cooling magma.
cyanobacteria
Single celled prokaryotes that were extremely abundant in the Precambrian and that changed the atmosphere to one containing oxygen.
cyclone
Wind system that rotates around a low pressure center.