Outdoor Glossary: G
gabion
(1) Steel wire-mesh basket to hold stones or crushed rock to
protect a bank or bottom from erosion. (2) (SMP) Structures composed of masses
of rocks, rubble or masonry held tightly together usually by wire mesh so as to
form blocks or walls. Sometimes used on heavy erosion areas to retard wave
action or as a foundation for breakwaters or jetties.
gage
See tide gauge.
gale
A wind between a strong breeze and a storm. A continuous wind
blowing in degrees of moderate, fresh, strong, or whole gale and varying in
velocity from 28 to 30 nautical miles per hour.
galley
The space on a boat that would be referred to as the kitchen
gallinaceous birds
synonymous with upland game birds.
galofaro
A whirlpool in the Strait of Messina; at one time called
Charybdis.
game animal
any wild animal that can be legally hunted or
trapped.
game species
Any species of wildlife or fish that is harvested
according to prescribed limits and seasons.
ganglion
A special rig used for bottom fishing that utilizes
multiple hooks in return giving the angler the ability to catch more than one
fish at a time
gap
The area between the point and the shank of a hook
gape
Base of the bill where the mandibles join. Synonym(s):
commissure, rictus.
gars
Primitive ray-finned freshwater fishes of North and Central
America and Cuba. Characterized by elongated jaws and heavy ganoid scales.
gas purged pressure gauge
A type of analog tide gauge in which gas,
usually nitrogen, is emitted from a submerged tube at a constant rate.
Fluctuations in hydrostatic pressure due to changes in tidal height modify the
emission rate for recording. Same as bubbler tide gauge.
gauge
A device for measuring the water level relative to a
datum.
gear
Any tools used to catch fish, such as hook and line, trawls,
gill nets, traps, spears, etc
gear ratio
In reference to the amount of times that the spool of a
reel rotates while the handle is rotated once.
generating area
In wave forecasting, a continuous area of the water
surface over which the wind blows in essentially the same direction. Sometimes
used synonymously with fetch length.
generating force mechanism
Causing waves formation such as
gravitational attraction.
generation of waves
(1) The creation of waves by natural or
mechanical means. (2) The creation of and growth of waves by a wind blowing over
a water surface for a certain length of time. The area involved is called the
generating area or fetch.
geodesy (or geodetics)
The science of dealing with the
investigation of scientific questions connected with the shape and dimensions of
the Earth.
geodetic datum
See National Geodetic Vertical Datum of 1929.
Geographic Information System (GIS)
A system of spatially
referenced information, including computer programs that acquire, store,
manipulate, analyze, and display spatial data.
geoid
The equipotential surface of the Earths gravity field which
best fits, in the least squares sense, mean sea level.
geology
The science which treats of the origin, history and
structure of the Earth, as recorded in rocks; together with the forces and
processes now operating to modify rocks.
geomorphic processes
Processes that change the form of the earth,
such as volcanic activity, running water, and glacial action.
geomorphology
(1) That branch of physical geography which deals
with the form of the Earth, the general configuration of its surface, the
distribution of the land, water, etc. (2) The investigation of the history of
geologic changes through the interpretation of topographic forms.
geophysics
The study of the physical characteristics and properties
of the Earth.
geopotential
The unit of geopotential difference, equal to the
gravity potential of 1 meter squared per second squared, m / s, or 1 joule per
kilogram, J / kg.
geopotential (equipotential) surface
A surface that is everywhere
normal to the acceleration of gravity.
geopotential anomaly (delta D)
The excess in geopotential
difference over the standard geopotential difference [at a standard specific
volume at 35 parts per thousand (/..) and 0 degrees C] between isobaric
surfaces. See geopotential and geopotential topography.
geopotential difference
The work per unit mass gained or required
in moving a unit mass vertically from one geopotential surface to another. See
geopotential, geopotential anomaly, and geopotential topography.
geopotential topography
The topography of an equiscalar (usually
isobaric) surface in terms of geopotential difference. As depicted on maps,
isopleths are formed by the intersection of the isobaric surface with a series
of geopotential surfaces. Thus, the field of isopleths represents variations in
the geopotential anomaly of the isobaric surface above a chosen reference
isobaric surface (such as a level of no motion).
geostrophic flow
A solution of the relative hydrodynamic equations
of motion in which it is assumed that the horizontal component of the Coriolis
force is balanced by the horizontal component of the pressure gradient
force.
gestation period
the period of time during which young develop
inside the mother's body prior to birth. The gestation period for a human is 9
months, while the gestation period for a red fox is 7-1/2 weeks.
gill
Respiratory organ of many aquatic animals; a filamentous
outgrowth well supplied with blood vessels at which gas exchange between water
and blood occurs.
gill membranes
Membranes along the ventral and posterior margin of
the operculum (gill cover) which function in respiration; they are supported by
the branchiostegal rays
gill nets
A flat net suspended vertically in the water with meshes
that allow the head of a fish to pass but entangle it at withdrawal; invented
circa 800 A.D. and used extensively by Native American fishers in the Great
Lakes region.
gill rakers
Bony, finger-like projection of the gill arch on the
opposite side from the red gill filaments which function in retaining food
organisms; they vary greatly in number and length and are important in the
classifications and identification of fishes
gimbals
A pair of rings and axles that will keep an object along a
level plane regardless of the pitch and movement of the object to which the
gimbals are anchored
GIS (geographic information systems)
GIS is both a database
designed to handle geographic data as well as a set of computer operations that
can be used to analyze the data. In a sense, GIS can be thought of as a higher
order map.
Global Positioning System (GPS)
A navigational and positioning
system developed by the U.S. Department of Defense, by which the location of a
position on or above the Earth can be determined by a special receiver at that
point interpreting signals received simultaneously from several of a
constellation of special satellites.
gonys
Lowermost ridge on lower mandible.
graded bedding
An arrangement of particle sizes within a single
bed, with coarse grains at the bottom of the bed and progressively finer grains
toward the top of the bed.
gradient
(1) A measure of slope (soil- or water-surface) in meters
of rise or fall per meter of horizontal distance. (2) More general, a change of
a value per unit of distance, e.g. the gradient in longshore transport causes
erosion or accretion. (3) With reference to winds or currents, the rate of
increase or decrease in speed, usually in the vertical; or the curve that
represents this rate.
gradient flow
A solution of the relative hydrodynamic equations of
motion in which only the horizontal Coriolis, pressure gradient, and centrifugal
forces are considered.
graphite
An extremely light and flexible material used to make rod
blanks and rod components
grass carp
rather slim body. Dark green to brownish above;
yellowish below. Frontal mouth with no barbels. Large scales. Size: Most are
5-15 pounds; potential much larger. World record 65 pounds, 14 ounces
gravel
(1) Loose, rounded fragments of rock, larger than sand, but
smaller than cobbles. (2) Small stones and pebbles, or a mixture of these with
sand.
gravitational tide
Same as equilibrium tide.
gravity wave
A wave whose velocity of propagation is controlled
primarily by gravity. Water waves more than 5 cm long are considered gravity
waves. Waves longer than 2.5 cm and shorter than 5 cm are in an indeterminate
zone between capillary and gravity waves. See ripple.
great diurnal range (Gt)
The difference in height between mean
higher high water and mean lower low water. The expression may also be used in
its contracted form, diurnal range.
great tropic range (Gc)
The difference in height between tropic
higher high water and tropic lower low water. The expression may also be used in
its contracted form, tropic range.
greater secondary coverts
Feathers overlying bases of
secondaries.
Greenwich argument
Equilibrium argument computed for the meridian
of Greenwich.
Greenwich interval
An interval referred to the transit of the Moon
over the meridian of Greenwich as distinguish from the local interval which is
referred to the Moon's transit over the local meridian. The relation in hours
between Greenwich and local intervals may be expressed by the formula: Greenwich
interval = local interval + 0.069 L where L is the west longitude of the local
meridian in degrees. For east longitude, L is to be considered negative.
Gregorian calendar
The modern calendar in which every year
divisible by 4 (excepting century years) and every century year divisible by 400
are bissextile (or leap) years with 366 days. All other years are common years
with 365 days. The average length of this year is, therefore, 365.242,5 days
which aggrees very closely with the length of the tropical year (the period of
changes in the seasons). The Gregorian calendar was introduced by Pope Gregory
in 1582, and immediately adopted by the Catholic countries in place of the
Julian calendar previously in use. In making the change it was ordered that the
day following October 4, 1582, of the Julian calendar be designated October 15,
1582, of the Gregorian calendar; the 10 days being dropped in order that the
vernal equinox would fall on March 21. The Gregorian calendar was not adopted by
England until 1752, but is now in general use throughout the world.
groin
(1) A shore-protection structure (built usually to trap
littoral drift or retard erosion of the shore). It is narrow in width (measured
parallel to the shore) and its length may vary from tens to hundreds of meters
(extending from a point landward of the shoreline out into the water). groins
may be classified as permeable (with openings through them) or impermeable (a
solid or nearly solid structure). (2) (SMP) A barrier-type structure extending
from the backshore or stream bank into a water body for the purpose of the
protection of a shoreline and adjacent upland by influencing the movement of
water and/or deposition of materials.
groin bay
The beach compartment between two groins.
groin system
A series of groins acting together to protect a
section of beach. Commonly called a groin field.
ground fire
A fire that burns along the forest floor and does nor
affect trees with thick bark or high crowns.
ground Penetrating Radar (GPR)
A geophysical technology that uses
radio waves to detect buried objects and the internal structure of landforms.
Ground swell: (1) Long high swell in deep water. (2) Also, this swell as if
rises to prominent height in shoal water.
ground water
Subsurface water occupying the zone of saturation. In
a strict sense the term applied only to water below the water table.
groundfish
Fishes that primarily inhabit the benthic environment,
such as flatfish
group selection
A method of tree harvest in which trees are removed
periodically in small groups. This
group velocity
The velocity at which a wave group travels. In deep
water, it is equal to one-half the individual wave velocity.
Guiana Current
An Atlantic Ocean current setting northwestward
along the north-east coast of South America.
guides
The loops on a rod through which the line runs
Guinea Current
An Atlantic Ocean current setting eastward along the
west central coast of Africa. A continuation of the Equatorial Counter Current
of the Atlantic Ocean.
gular
Behind the chin and between the sides of the lower jaw
gular region
Between the chin and the foreneck.
Gulder
Local name given to the double low water occurring on the
south coast of England. See double tide.
gulf
A relatively large portion of sea, partly enclosed by
land.
Gulf Coast Low Water Datum (GCLWD)
A tidal datum. Used as chart
datum from November 14, 1977, to November 27, 1980, for the coastal waters of
the Gulf coast of the United States. GCLWD is defined as mean lower low water
when the type of tide is mixed and mean low water (now mean lower low water)
when the type of tide is diurnal. See National Tidal Datum Convention of
1980.
Gulf Coast Low Water Datum line
The line on a chart or map which
represents the intersection of the land with the water surface at the elevation
of Gulf Coast Low Water Datum.
Gulf Stream
A North Atlantic Ocean current setting northeastward
off the east coast of the United States. A segment of the Gulf Stream System,
the Gulf Stream extends from the region off Cape Hatteras to an area southeast
of the Grand Banks at about latitude 40 north, longitude 50 west. It continues
the flow of the Florida Current to the North Atlantic Current.
Gulf Stream System
The continuous current system composed of the
Florida Current, Gulf Stream, and North Atlantic Current.
gulls
refers to all Larus and Rissa (Family Laridae). True gulls
and kittiwakes.
gut
The alimentary canal. A term used when describing fish
larvae
gut
(1) A narrow passage such as a strait or inlet. (2) A channel
in otherwise shallow water, generally formed by water in motion.
guyot
Flat-topped seamount.
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