Geoscience Reference
In-Depth Information
Climax vegetation The vegetation within an area that has
reached its ultimate complexity. 254
Coal A solid fossil fuel that consists of carbonized plants
and animals. 318
Cold front A frontal boundary where cold air is advancing
into relatively warm air. This front is typically associated with
intense rain of short duration. 172
Colloids Very small (10 nanometers to 1 micrometer),
evenly divided solids that do not settle in solution. 279
Colluvium Unconsolidated sediment that accumulates at the
base of a slope. 381
Composite volcano A large, steep-sided volcano that grows
through progressive volcanic eruptions, which are usually
explosive, and consists of layers of volcanic debris. 361
Condensation The process through which water changes
from the vapor to liquid phase. 140
Condensation nuclei Microscopic dust particles
around which atmospheric water coalesces to form
raindrops. 152
Conduction The transfer of heat energy from one substance
to another by direct physical contact. 71
Cone of depression The cone-shaped depression of the
water table that occurs around a well. 398
Confluence The place where two streams join
together. 412
Conformal projection A map that maintains the correct
shape of features on the Earth but distorts their relative size to
one another. 24
Conglomerate Sandstone that contains a wide variety of
particle sizes. 315
Constant gases Atmospheric gases such as nitrogen,
oxygen, and argon that maintain relatively consistent levels in
space and time. 63
Continental A place that is surrounded by a large body
of land and that experiences a large annual range of
temperature. 94
Continental crust Granitic part of the Earth's crust that
makes up the continents. Continental crust averages about
40 km (25 mi) in thickness and is also called sial because it
consists largely of silica and aluminum. 308
Continental drift The theory that the continents
move relative to one another in association with plate
tectonics. 335
Continental glacier An enormous body of flowing ice that
covers a significant part of a large landmass. 455
Contours Isolines that connect points of equal
elevation. 30
Convection A circular cell of moving matter that contains
warm material moving up and cooler matter moving down. 71
Convectional uplift Uplift of air that occurs when bubbles of
warm air rise within an unstable body of air.
Convergent uplift Uplift of air that occurs when large bodies
of air meet in a central location. 157
Coral reefs Resistant marine ridges or mounds consisting
largely of compacted coral together with algal material and
biochemically deposited calcium carbonates. 527
Cordilleran Ice sheet The ice cap that covered much of the
mountains in the northwestern part of North America during
the Pleistocene Epoch. 466
Coriolis force The force created by the Earth's rotation that
causes winds to be deflected to the right in the Northern Hemi-
sphere and to the left in the Southern Hemisphere. 112
Counterradiation Longwave radiation that is emitted toward
the Earth's surface from the atmosphere.
64
The highest point of a dune.
490
Crest
Crevasse
A deep crack in a glacier.
450
Individual puffy clouds that develop due to
Cumulus clouds
convection. 153
Cyclogenesis The sequence of atmospheric events along the
polar jet stream that produces midlatitude cyclones.
174
Low-pressure systems.
108
Cyclones
D
Dam A barrier that blocks or restricts the downstream
movement of a stream. 440
Debris flow A rapidly flowing and extremely powerful mass
of water, rocks, sediment, boulders, and trees. 386
Debris slide A mass-wasting process in which slope
failure occurs along a plane that is roughly parallel to the
surface. 384
Decomposers Organisms that consume dead or decaying
organic substances for nutrition. 236
Deflation Removal of sediment from a surface by wind
action. 487
Deflation hollow
A depression created by wind
erosion. 487
Deforestation The removal of trees for economic or
agricultural purposes. 256
Degradation The topographic lowering of a stream channel
by stream erosion. 423
Delta A low, level plain that develops where a stream
flows into a relatively still body of water so that its velocity
decreases and alluvial deposition occurs. 436
Dendrochronology The dating of past events and variations
in the environment and climate by studying the annual growth
rates of trees. 219
Deposition The process by which water vapor changes
directly to ice. 140
Desert pavement A resistant, pavement-like surface created
when fine particles blow away and coarse sediment such as
pebbles and gravel is left behind.
157
493
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