| Accessibility
A term used to describe the relative ease or difficulty
in reaching a waterfall.
Angle of Repose
The steepest slope in which a particular sediment will
lie motionless without falling or sliding.
Arroyo
A flat-floored, often vertically walled channel of an
intermittent stream typical of semiarid climates. Commonly
observed in the southwestern United States. Synonymous
with Wadi and Wash.
Basalt
A fine-grained igneous (volcanic) rock, dominated by
dark-colored minerals, consisting of plagioclase feldspars
(over 50 percent) and ferro-magnesian silicates. Basalts
and andesites represent about 98 percent of all extrusive
rocks on earth. Commonly seen in regions synonymous
with volcanic activity (Iceland, New Zealand, Northwestern
North America, Japan).
Base
The bottom of a waterfall formation.
Bedrock
The solid rock substrate beneath which lies beneath
more permeable materials (such as soil, gravel or water).
Often the term is used to describe the rock formation
which a waterfall descends over.
Block
A form of a waterfall. A waterfall in a Block
form occurs over a wide breadth of the stream.
The waterfall must be wider than it is tall. A
waterfall with this form does not have to be a solid
sheet of water across it's entire width.
Boulder Garden
A term used to describe a steep section of a stream,
where the water cascades over, under, and between large
boulders which line the riverbed.
Brink
The top of a waterfall. Also referred to as the Crest.
Bushwhack
To clear a path through thick vegetation. More commonly,
this term is used to describe any off-trail, or cross
country travel, which involves navigating heavily forested
ground, in which a large, sharp blade (ex. machete)
would aid in travel.
Butte
A steep sided and flat topped hill formed by erosion
of flat laying strata where remnants of a resistant
layer protect the softer rocks underneath. Also applied
to small, usually dormant or extinct volcanoes known
as Cinder Cones, which usually stand less than 1000
feet above the outlying plain.
Canyon
A deep, narrow, steep-sided (often vertical-walled)
valley, usually with a watercourse flowing through it.
Caprock
An overlying rock layer that is more resistant to weathering
than formations located beneath it. Waterfalls dropping
over cap rock formations tend to be classified as a
Plunge, Block or Curtain form.
Cascade
A form of a waterfall. A waterfall of a Cascade form
descends over, gradually sloping rocks, a series of
small steps in quick succession, or a rugged sloping
surface of some kind. Cascades can be both gradual
and steep.
Cataract
A terms used to describe vertical waterfalls which possess
a large volume of water. Often used synonymously with
"Plunge".
Cirque
A steep-walled hollow, shaped like a half-bowl or amphitheater,
formed by glaciation and frost wedging. Cirques are
found in mountainous regions populated with glaciers,
or which have had a history of being glaciated. The
term Headwall can often be used interchangeably with
Cirque, but not vice versa.
Conglomerate
Detrital sedimentary rock made up of compressed, poorly
sorted dust, sand, pebbles and small stones. Conglomerate
rock looks like sandstone with large pebbles and small
stones infused throughout.
Contour Lines
A line on a topographic map representing a certain elevation
at a certain location. Space between two contour lines
represents a change in elevation by the interval the
contour lines represent.
Contours
Contours represent the vertical, or third, dimension
on a topographic map. They show the shape and size of
physical features such as mountains, hills and valleys.
Crest
See "Brink".
Current
A term used to describe the movement of water in a stream.
Curtain
A form of a waterfall. Curtain waterfalls occur along
a wide breadth of stream where the falls must be taller
than it is wide.
Discharge
The amount of water to pass a given point on a stream,
per unit of time. Usually expressed in cubic feet or
cubic meters of water per second.
Erosion
Movement of earthen material from one place to another
on earth's surface. Natural causes of erosion include
gravity, water movement, glaciation, and wind.
Escarpment
An often vertical, or near vertical, slope or cliff
at the edge of a plateau or ridge, which often stretches
for several miles. Usually formed by erosion.
Face
The vertical surface of a cliff. In this case, the rock
surface where the water is falling. Also known as Cliff
Face.
Fan
A form of a waterfall. Waterfalls of a Fan form occur
when the breadth of the water in the waterfall increases
during it's decent, causing the base of the falls to
appear much wider than the top of the falls.
Fjord
A deep, steep-walled, U-shaped valley formed by glaciation,
which has been flooded by seawater. Typically, waterfalls
in this formation drop from hanging valleys. Fjords
are commonly found in New Zealand, Canada, southern
Argentina and Norway.
Glacier
A large mass of ice which persists throughout the year,
and moves slowly downslope in a liquid manor by it's
own weight. Glaciers are formed in areas where the winter
snow doesn't have a chance to melt, and consecutive
snowfalls accumulate and compress into ice.
Gneiss
A coarse-grained regional metamorphic rock that shows
compositional banding and parallel alignment of minerals.
Gorge
A deep, usually narrow ravine, or canyon, often with
vertical walls, usually with a watercourse running through
it.
Gradient
The slope of stream bed or land surface within a given
distance. Expressed in percentage, feet per mile, meters
per kilometer, or in degrees.
Granite
A coarse-grained, intrusive igneous (volcanic) rock
composed of quartz, orthoclase feldspar, sodic plagioclase
feldspar, and micas. Waterfalls flowing over granitic
bedrock are often characterized by water sculpture and
polishing.
Greywacke
A variety of sandstone generally characterized by hardness,
dark color, and angular grains of quartz, feldspar,
and small rock fragments set in a matrix of clay-sized
particles. Also known as Lithic Sandstone.
Hachures
A depression indicated on a topographic map by short
dashes, which point towards the center of the depression.
Often used to mark rock quarries or volcanic craters.
Hanging Valley
A valley most often formed as a result of glaciation,
where a large glacier erodes a valley, at a perpendicular
angle to the hanging valley, to a deeper extent. The
result is that of a small valley intersecting a larger
valley at an elevation noticeably above the bottom of
the larger valley. Hanging valleys can be, but are not
always, eroded by a glacier.
Height
The measurement of a waterfall from it's brink to it's
base. Often not an exact science, as placing the brink
and base of a waterfall is sometimes ambiguous and arbitrary.
Horsetail
A form of a waterfall. Horsetail waterfalls are characterized
by the constant or semi-constant contact the water keeps
with the bedrock as it falls. Horsetail waterfalls
can be almost vertical, as well as very gradual.
Igneous Rock
An aggregate of interlocking silicate minerals formed
by cooling and solidification of magma or lava.
Igneous rocks are formed by volcanic processes.
Joints
Breaks in rock mass with no relative movement of rock
on opposite sides of the break.
Karst Topography
Irregular topography characterized by sink holes, caves,
streamless valleys, and underground streams; all developed
by the actions of surface and underground water in soluble
rocks, such as limestone or soapstone.
Knickpoint
A distinct point of sudden or abrupt steepening in the
gradient of a streambed, often indicating the presence
of a waterfall.
Limestone
Sedimentary rock composed largely of the mineral Calcite
(CaCO3), formed by either organic or inorganic processes.
Most limestones have clastic texture, but nonclastic,
particularly crystalline, textures are common.
Marble
Metamorphic rock of granular texture, with no rock cleavage,
and composed of Calcite (Marble), Dolomite, or both.
Metamorphic Rock
Any type of rock which changes in texture or composition,
after it's original formation, as a result of extreme
heat, pressure, or chemically active fluids.
Meters of Head
A term used by the hydropower industry to describe
the elevation change between two points on a watercourse,
often above and below a large waterfall, which would
result in the production of a given amount of electricity.
Measurements of Meters of Head are often not a true
representation of the actual height of a waterfall,
but are commonly, and incorrectly used as such.
Orientation
The direction a waterfall faces, or the direction in
which a watercourse flows over a waterfall.
Plateau
A typically extensive land area, having a relatively
level surface raised sharply above adjacent land on
at least one side.
Plunge
A form of a waterfall. The classic and overly cliched
waterfall form, where the water drops vertically, losing
most, or all contact with the rock face. This waterfall
form has also been referred to as a "Cataract"
and a "Vertical" form waterfall.
Plunge Pool
A pool at the base of a waterfall formed by hydraulic
erosion.
Punchbowl
A form of a waterfall. Punchbowl waterfalls, coined
from the famous Punch Bowl Falls in Oregon, occur where
the stream is constricted to a narrow breadth and is
forcefully shot outward and downward into a large pool.
Quartzite
Metamorphic rock commonly formed by metamorphism of
sandstone and composed of quartz. No rock cleavage.
Quartzite breaks through sand grains in contrast to
sandstone, which breaks around sand grains.
Rapids
A section of a stream where the current has a moderate
velocity, the surface is broken by extruding rocks and
debris, producing frothy "whitewater", and
the gradient of the stream remains shallow.
Run
The horizontal distance in which the elevation change
of a waterfall takes place. Also know as Runout.
Sandstone
Detrital sedimentary rock formed by cementation of individual
grains of sand size and commonly composed of mineral
quartz.
Schist
Metamorphic rock dominated by fibrous or platy minerals.
Schist has a schistose plain of cleavage, and is product
of regional metamorphism.
Scree
see Talus.
Sedimentary Rock
Rock formed from accumulations of sediment, which may
consist of rock fragments of various sizes, remains
or products of animals or plants, products of chemical
action or of evaporation, or any mixture of these. Stratification
is the single most characteristic feature of sedimentary
rocks, which cover about 75 percent of earth's land
area.
Segmented
A form of a waterfall. Segmented waterfalls occur where
the stream is broken into two or more channels before
descending over the cliff, causing multiple falls to
occur side by side.
Shale
Fine-grained, detrital sedimentary rock made up of silt
and clay sized particles. Contains clay minerals as
well as particles of quartz, feldspar, calcite, dolomite,
and other minerals. Shale has a parallel plain of cleavage.
Sinkhole
A depression in the surface of the earth caused by the
collapse of the roof of a cave or cavern.
Slate
Fine-grained metamorphic rock with well-developed slaty
cleavage. Formed by low-grade regional metamorphism
of shale.
Slide
A form of a waterfall. Similar to a cascade, a Slide
type waterfall descends a smooth, gradual bedrock surface.
Slide waterfalls maintain constant contact with the
bedrock, and are often seen in areas where granitic
rocks are common.
Spring
A feature where the water table intersects the land
surface and water flows from underground at a more or
less continuous rate.
Stream
A constantly moving body of water, confined to the lowest
possible depression in the earth's surface. The term
Stream on this site refers to any size watercourse.
Synonymous with Brook, Creek and River.
Talus
A slope consisting of rocks and boulders which have
cleaved off of an adjacent cliff face. Talus is often
found at the bottom of a waterfall. The term "talus"
is also widely used to describe rock debris itself.
Synonymous with Scree.
Tiered
A form of a waterfall. Tiered waterfalls are characterized
by multiple distinct drops in relatively close succession
to one another. Whether or not a waterfall with
two visible drops counts as a tiered waterfall is up
to the beholder.
Topographic Map
A schematic drawing representing landforms indicated
by conventionalized symbols, such as contours and hachures.
Often referred to as a Topo Map. See also: Contour Line,
Contours, and Hachures.
Travertine
A terrestrial deposit of limestone formed in caves and
around hot springs where cooling, carbonate-saturated
groundwater is exposed to the air.
Tributary
A smaller stream which feeds into a larger stream. The
size of the smaller stream is relative to that of the
larger stream (the smaller stream is always the tributary).
Valley
An elongated depression of the earth's surface, usually
between ranges of hills or mountains. Also, an area
drained by a stream or river and their tributaries.
Watershed
Also known as a Drainage Basin. Area from which a given
stream and its tributaries receive water.
Width
The width of a waterfall formation, sometimes measured
at the brink, sometimes taken as an average width of
the waterfall. |
