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F
fault - (4) a fracture or fracture zone in rock strata resulting
from strain and with observable displacement.
Federal Land Policy and Management Act (FLPMA) - (3) The
act that (a) set out for the Bureau of Land Management standards
for managing the public lands, including land use planning, sales,
withdrawals, aquisitions and exchanges; (b) authorized the setting
up of local advisory councils representing major citizens groups
interested in land use planning and management; (c) established
criteria for review of proposed wilderness areas; and (d) provided
guidelines for other aspects of public land management such as grazing.
first order tributary - (3) a non-branching headwater channel
segment.
fishery - (3) habitat that supports the propagation and
maintenance of fish.
flocculent - (4) a substance that causes suspended particles
to aggregate or clump together. The higher mass causes the aggregated
clumps to settle. Flocculents are used to reduce high concentrations
of fine silt-size and clay-size suspended sediment,
particles whose slow settling rate makes them otherwise very difficult
to remove. See also sediment/settling pond.
flood plain - (3) level streamside land that may be subject
to flooding.
flood recurrence interval - (4) the average length of time
within which a specific magnitude of flood will occur once. Predicted
from the historic record and/or the site-specific runoff and climatic
conditions of the contributing watershed. Important factors include
variations in storm duration and the intensity of rain, rain-on-snow,
and snow melt events. A one-in-200-year flood event is a slow event
that has an average recurrence interval of 0.005.
flotation - (1) the separation of minerals from each other
and from waste matter by inducing (through the use of reagents)
relative differences in their abilities to float in a frothy liquid
medium. The process will separate all metallic sulfides or elemental
metals. If necessary, differential flotation can be used on complex
ores. In such an ore, each sulfide mineral, such as copper, lead
and zinc, can be separated from others. Three types of flotation
exist:
- surface tension flotation - based on the tendency that
many minerals, particularly sulfide minerals, when in a fine state
of division, exhibit a reluctance to be wetted by water and tend
to float on its surface.
- bulk oil flotation - based on the tendency for certain
minerals to be wetted preferentially by oil in the presence of
water. Once wetted by oil, they tend to form into sperules or
into granules which, being lighter than an equal bulk of water,
tend to rise to the surface where they can be recovered.
- froth flotation - based on the tendency for a mixture
of oil, finely divided ore and air to rise to the surface of water.
The mixture of ore, oil, water and excess air is violently agitated,
forming a froth that rises to the surface of water.
(2) the method of mineral separation which a froth created in water
by a variety of reagents floats some finely crushed minerals,
wheras other minerals sink. A commonly used method for concentration
of valuable minerals from gangue minerals. (4) a milling
process using surface active chemicals to selectively modify some
mineral surfaces causing them to be attached to air bubbles and
float, while others do not, and sink. This process allows the selective
concentration and recovery of the valuable minerals. Pre-treatments
include grinding and addition of the reagents.
flow regimes - (3) characteristics of stream discharge over
time. The natural flow regime is the regime that occurred historically.
fluvial - (2)(3) pertaining to or produced by the action
of a stream or a river.
forb - (3) an herbaceous plant that is not a grass, sedge
or rush.
fracture - (4) (a) a crack, joint, fault or other break
in rocks, (b) the breaking of a mineral other than along planes
of cleavage.
free water - (3) ground water free to move in response to
gravity.
fugitive dust - (3) particulate matter emissions that do
not pass through a stack, chimney, vent, pipe or similar opening.
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