Geoscience Reference
In-Depth Information
known Tertiary period and ending in the
Quartenary
period and is roughly divided in half between the older
Palaeogene
and younger
Neogene
periods.
Chamaephytes
Plants which hug the ground surface
and where buds are located on the ground surface.
Channel flow
The confinement and concentration of
surface water movement in a fluvial channel.
Channel network
The pattern and connectivity of all
channels draining a
catchment
.
Channel segment
A short length of fluvial channel
selected for the purpose of assessing or modelling relations
between channel geometry,
inclined floor or rock basin and barrier, abundant signs
of glacial scour and a terminal moraine.
Cirque glacier
A small mountain glacier which excavates
and occupies a
cirque
; its diminutive size renders it
particularly sensitive to local climate and climatic change.
Clast
A rock fragment derived by weathering and
erosion from existing rock mass; individual clasts more
than 2 mm in diameter are often distinguished from
smaller fragments, which form a rock matrix.
Clastic sediment
A sediment composed of rock
fragments, regardless of their individual size, rather than
chemical precipitates or biogenic material; it may become
lithified by the precipitation of a chemical cement.
Clay minerals
Crystalline colloids smaller than 2 mm in
diameter; mostly new minerals formed by
weathering
and
soil formation processes
, and very important in
determining the properties of soils.
CLEAR (Climate and Environment in Alpine Regions)
a
research project established in 1992 by the Swiss National
Science Foundation to explore the potential impacts of
climate change on alpine regions.
Cleavage
A rock texture in fine-grained materials with
parallel microplanes or fractures, dependent on individual
platy
crystal structure or the alignment of platy minerals
in rock mass; the term is also used to describe the tendency
for such rocks to split along these planes.
Climax community
The
plant community
which marks
the end point of a
succession
; it is relatively stable and in
equilibrium with prevailing environmental conditions.
Climax pattern
The pattern of climax communities
which develop in a defined area.
Coastal cell
A discrete unit of coastline identified for
management purposes, recognizing the integration of
coast-parallel as well as coast-normal water and sediment
transfers and multiple use by human socioeconomic
activity.
Coastal plain
A gently sloping land surface which forms
a continuum with the
continental shelf
and is susceptible
to small sea-level changes; it is likely to be wide on
trailing-
edge
(passive margin) coasts and narrow on
leading-edge
(convergent margin) coasts.
Coastline
The boundary between land and sea or, more
precisely, a permanently exposed land surface and the
highest occurrence of storm waves.
Cohesion
The intermolecular bonding of constituents of
Earth materials by chemical, magnetic and electrostatic
forces.
Cohesive strength
The portion of total rock mass
strength dependent on the extent of
cohesion
developed
between particles or crystals by intermolecular forces.
stream discharge and
sediment transfer.
Chelate
A complex organic compound containing
a central metallic ion (e.g.
iron,
calcium,
copper)
surrounded by organic chemical groups.
Chelating agent
An organic substance capable of
weathering metallic ions from rock, or moving metallic
ions in soils.
Chelation
The process of forming
chelates
, usually by
means of organic acids or organic salts.
Chemical energy
A form of energy bound up within the
chemical structure of a substance.
Chemical sediment
A non-
clastic
and often crystalline
sediment, derived from mineral or organic sources and
formed by precipitation from a solution or suspension.
Chemical weathering
The disaggregation of rock mass
caused by chemical alteration of some or all of its
constituent minerals in the conditions prevailing at or
near the land surface.
Chinook
A dry downflow in the lee of the Rocky
Mountains, warming adiabatically on descent and warmer
in absolute terms at any given altitude than on its
windward ascent.
Chionophilous
Able to survive very long winter seasons
completely covered by snow; snow-loving.
Chlorite
A 2 : 1 : 1 clay mineral with 2 : 1 mica units held
together by an aluminium (gibbsite) sheet.
Chlorosis
Yellowing of green leaves caused by lack of an
essential plant nutrient or by toxic amounts of acid rain.
Chute
A narrow channel containing a fast-flowing
stream in a braided river; or a steep, rock-lined channel
between rock pinnacles which funnels debris on to lower
slopes.
Cinder
A vesicular
pyroclastic
fragment ejected during
volcanic eruption.
Circular sliding
A slope failure whose failure surface is
along the arc of a circle.
Cirque
A rock basin excavated into a mountainside by
the erosive power of a cirque glacier and possessing some
or all of the following: steep retaining rock walls, a gently
