Outdoor Glossary: U
unconformity A surface that represents a break in the geologic
record, with the rock unit immediately above it being considerably younger than
the rock beneath. There are three major aspects to consider: (1) Time. An
unconformity develops during a period of time in which no sediment is deposited.
This concept equates deposition and time, and an unconformity represents
unrecorded time. (2) Deposition. Any interruption of deposition, whether large
or small in extent, is an unconformity. This aspect of unconformity pre-supposes
a standard scale of deposition which is complete. Major breaks in
sedimentation can usually be demonstrated easily, but minor breaks may go
unrecorded until highly detailed investigations are made. (3) Structure.
Structurally, unconformity may be regarded as planar structures separating older
rocks below from younger rocks above, representing the break as defined in (1)
and (2) above. A plane of unconformity may be a surface of weathering, EROSION
or denudation, or a surface of non-deposition, or possibly some combination of
these factors. It may be parallel to the upper strata, make an angle with the
upper strata, or be irregular. Subsequent Earth movements may have folded or
faulted it.
unconsolidated In referring to sediment grains, loose, separate, or
unattached to one another.
underburn A burn by a surface fire that can consume ground
vegetation and "ladder" fuels.
undercutting erosion of material at the foot of a cliff or bank,
e.g., a sea cliff, or river bank on the outside of a meander. Ultimately, the
overhang collapses, and the process is repeated.
underparts Belly, undertail coverts, chest, flanks, and
foreneck.
understory The trees and woody shrubs growing beneath the overstory
in a stand of trees.
undertail coverts Feathers covering underside of base of tail.
Synonym(s): crissum.
undertow (1) A current below water surface flowing seaward; the
receding water below the surface from waves breaking on a shelving beach. (2)
Actually undertow is largely mythical. As the BACKWASH of each wave flows down
the beach, a current is formed which flows seaward. However, it is a periodic
phenomenon. The most common phenomena expressed as undertow are actually rip
currents.
underwater gradient The slope of the sea bottom. See slope.
underwing Underside of wing.
undisturbed water level Same as still water level.
uneven aged management - Actions that maintain a forest or stand of
trees composed of intermingling trees that differ markedly in age. Cutting
methods that develop and maintain uneven-aged stands are single-tree selection
and group selection.
universal time (UT) Same as Greenwich mean time (GMT).
unregulated harvest Tree harvest that is not part of the allowable
sale quantity (ASQ). It can include the removal of cull or dead material or
non-commercial species. It also includes volume removed from non-suitable areas
for research, to meet objectives other than timber production (such as wildlife
habitat improvement), or to improve administrative sites (such as
campgrounds.)
unsuitable lands Forest land that is not managed for timber
production. Reasons may be matters of policy, ecology, technology, silviculture,
or economics
upbound from the Atlantic Ocean
updrift The direction to which the predominant longshore movement
of beach material approaches.
upland game birds nonmigratory birds found on terrestrial habitats.
These include prairie chickens, wild turkey, quails, pheasants, grouse,
partridges, and ptarmigans. Doves and American woodcock are considered
separately for purposes of this publication.
uplands Land above the mean high water line (shoreline) and subject
to private ownership, as distinguished from tidelands, the ownership of which is
prima facie in the state but also subject to divestment under state statutes.
See tidelands.
upper mandible Upper part of the bill.
upper mandibular tomia Cutting edges of upper mandible.
upperparts Back, rump, hindneck, wings, and crown.
uppertail coverts Feathers covering upperside of base of
tail.
upperwing Upperside of wing.
upwelling The process by which water rises from a deeper to a
shallower depth, usually as a result of offshore surface water flow. It is most
prominent where persistent wind blows parallel to a coastline so that the
resultant Ekman transport moves surface water away from the coast.
use, allowable An estimate of proper range use. Forty to fifty
percent of the annual growth is often used as a rule of thumb on ranges in good
to excellent condition. It can also mean the amount of forage planned to be used
to accelerate range rehabilitation.
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