Geoscience Reference
In-Depth Information
Fault A line or zone along which faulting has occurred
in rock mass.
Fault breccia Angular rock rubble lining a fault and
formed by shearing and crushing of a wider zone of rock
mass bounding the fault during movement.
Faulting The process of fracture or brittle failure of rock
with displacement of adjacent parts on either side of the
fault .
Feedback The property of a system such that, when
change is introduced via one of the variables in the system,
its transmission through the system leads back to a change
in the original variable.
Felsenmeer A German term for blockfield .
Felsic A mnenomic from fel dspar and si li c ate, which
identifies the silicate-rich igneous rocks characterized by
their light-coloured, acidic minerals.
Fetch The extent of open water over which a dominant
wind develops a wave system.
Field capacity The maximum volume of water held in
the voids of a soil when gravitational drainage is complete,
comprised of capillary and hygroscopic water.
Firn A stage in the transformation of snowpack towards
glacial ice, with a density of 0·4-0·5
Fluid stressing The erosive power of a stream contri-
buted by fluid shear stress at the stream bed.
Flysch Submarine turbidite sediments eroded from an
orogenic belt during uplift and therefore located in
adjacent trench or back-arc zones.
Föhn
An equivalent of
the chinook wind in the
European Alps.
Fold A compressional or gravitational plastic deforma-
tion of Earth materials which has bent and shortened a
previously planar mass.
Foliation A close-spaced planar texture in rock acquired
by the alignment of platy minerals during metamorphism .
Force
Mass
acceleration measured in newtons, N (SI
units).
Fore arc A zone lying between and parallel to the trench
and volcanic arc of a B-subduction zone, consisting of an
outer ridge and an inner basin.
Fore-arc basin A narrow marine basin lying just offshore
of a volcanic island arc in a B-subduction zone .
Foreshore That part of a beach lying between the low-
water mark and maximum high-tide mark.
Formation A world vegetation type dominated by plants
of similar life form and identified in a geographically
distinct area.
Fossil soil A soil formed in the past under environ-
mental conditions which no longer exist.
Fractional crystallization Separation of a magma during
cooling into distinctive, usually mineral-specific parts.
Fractionation
10 3 kg m -3 .
Fissure A wide fault or tension crack in the land surface
often associated with a linear volcanic eruption.
Fixation The transformation in soil of a plant nutrient
from an available to an unavailable state.
Fjord A long, deep rock basin excavated by an outlet or
valley glacier between high rock walls and flooded by the
sea during deglaciation.
Flandrian stage The current global temperate stage ,
more or less synonymous with the Holocene, which
commenced c. 10,000 years BP .
Flexural isostasy Localized isostatic adjustment
peripheral to, and in an opposite direction from, an area
of crustal loading or unloading; due to flexure or creep in
the lithosphere.
Flocculation The aggregation of individual suspended
clay particles into larger masses, with consequential
implications for their sediment dynamics.
Flood basalt An extensive basalt flow extruded from
continental rifts and fissures which forms distinctive
terrestrial land surfaces.
Flood plain A lowland land surface prone to episodic
river floods and associated alluvial sedimentation.
Flow regime The range of styles of stream flow and
their related bed forms and modes of sediment transport.
Flow tuff A lithified form of volcanic ash which once
moved as a pyroclastic flow and contains evidence of that
movement,
The separation of
a mixture into its
component elements and minerals.
Fragipan A dense pan-like subsoil horizon, indurated by
physical and/or chemical processes, and with a high bulk
density.
Free-living fixation Fixation of atmospheric nitrogen
into organic nitrogen compounds by soil micro-
organisms which live freely in the soil rather than existing
in association or symbiosis with a plant.
Friction strength The portion of rock or soil strength
dependent on the frictional contact between constituent
particles.
Frost heave Process of vertical and lateral movement in
periglacial soils in autumn due to expansion of water into
ice and vein-ice aggradation.
Frost shattering The fracture of rock mass attributed
to internal stress generated by expansion on freezing,
pore water migration to a freezing plane or hydration
in the permafrost environment; it is probable that
some form of fatigue is involved over many freeze-thaw
cycles.
Froude number
often in the form of
parallel extruded
An index of the type of flow in a stream.
minerals.
 
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