Geology and Waterfall Terminology

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Aquifer

An underground water system that is contained within the pores of rock and sediment. Wells and tap aquifer systems.

Angle of repose

The greatest angle of steepness a slope can have while still maintaining its sediment.

Anoxic

Lacking oxygen.

B

Bed

The bottom of a stream, usually bedrock.

Bedrock

The solid layers of rock found under sand, dirt or water.

Block

A type of waterfall, most commonly a curtain that occurs in a wide river.

Brink

The top of the waterfall. More specifically, the top edge from which water falls. Also referred to as the crest.

Brook

A stream, smaller than a creek, commonly considered to be fed by a natural spring.

C

Cairn

An unnatural pile of rocks, often organized, built as a landmark or work of art.

Calcium Carbonate

Calcium carbonate is a chemical compound, with chemical formula CaCO3. It is commonly used medicinally as a calcium supplement or as an antacid. Calcium carbonate is the active ingredient in agricultural lime. It is a common substance found as rock in all parts of the world and is the main component of seashells and the shell of snails. It is usually the principle cause of hard water. (courtesy of wikipedia.org)

Canadian Shield

A large area of exposed Precambrian rock in North America. The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. Diagram.

Canyon

A narrow, steep valley, ravine or canyon, walled by cliffs, often carved over time by water. A gully, ravine or gorge.

Caprock

The top layer of bedrock at the crest of the waterfall.

Cascade

A type of waterfall that flows down a rock face with many jumps. The slope is usually close to 45%. More consistent and defined jumps are commonly referred to as a staircase or tiered falls. Most cascade falls in NY are due to bedrock of soft shale stone.

Cataract

A large waterfall (by volume or height). Also used to describe river rapids with noticeable descent.

Causeway

A pathway or road, elevated by a bank, usually across water or wetland. See Otisco Lake.

Channel

An eroded portion of the stream bed that directs the stream flow. A channel can be a small groove or a large gorge.

Chute

A narrow path of water through rock. Usually turbulent and with high current.

Cirque

An amphitheatre-like, cliff-walled valley, carved by glaciers and enhanced by water erosion and ice cleavage. The highest cliff is often called the headwall.

Classical

A waterfall that is as wide as it is high.

Clastic rock

A type of rock formed from fragments of pre-existing rock.

Clay

A hydrous (wet) mix of aluminum and silicate minerals. Usually formed by weathering of silicate rocks (many sedimentary rocks, including shale). Clay retains its water better than mud, as the water is chemically bound to the minerals. This binding, along with the small size, allows for high plasticity. Clay formations will expand and contract depending on water content, yielding unstable geology.

Concretion

A bulbous mineral concretion usually found within a layer of sedimentary rock. Often called Turtle Stones. They are formed by minerals found within rock layer precipitating towards a nucleus (mineral or bone) and under great pressure, form a rock, harder than the surrounding rock.

Conglomerate

A type of sedimentary rock comprised of a variety of sand, pebbles, small stones and sometimes shells or fossils. Sometimes called a concretion.

Contour lines

The lines on a topographic (topo) map that indicate elevation. The closer together the lines are, the steeper the slope.

Crampons

Crampons are a framework of spikes that are attached to boots to provide traction on snow and ice. (courtesy of wikipedia.org)
It is recommended that you use crampons when hiking in gorges and stream beds in the winter.

Creek

A stream of small size.

Crest

The top of the waterfall. More specifically, the top edge from which water falls. Also referred to as the brink.

Current

The flow of water in a stream.

D

Discharge

A measurement of the amount of water in a stream that passes a certain point over a period of time. (Usually cubic feet/second).

Drainage Basin

See Watershed.

Drop

Any place along the stream where water falls from one point to another.  It could be a free-fall or maintain contact with rock behind, but the fall must be at a higher gradient then the surrounding stream’s gradient.

E

Ephemeral

Changing, not constant; often used in reference to bodies of water that hold water for part of the year and are dry at other times.

Erosion

Erosion is the displacement of solids (soil, mud, rock, and other particles) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case of bioerosion). (courtesy of wikipedia.org)

Erratics

Seemingly out-of-place boulders carried to their current location by glacier movement. Identifiable by their roundness and difference in composition from the bedrock.

Escarpment

In geology, an escarpment is a transition zone between different physiogeographic provinces that involves an elevation differential, often involving high cliffs. Most commonly, an escarpment, also called a scarp (from the German word scharf meaning sharp), is a transition from one series of sedimentary rocks to another series of a different age and composition. In such cases, the escarpment usually represents the line of erosional loss of the newer rock over the older. (courtesy of wikipedia.org) Specifically in Upstate NY, the Niagara, Onondaga and Portage escarpments contribute to most dramatic gorges and waterfalls. The Niagara Escarpment is responsible for Niagara Falls and the three falls of Rochester, NY. The Onondaga Escarpment contains Akron Falls, Chittenango Falls, Oatka Falls, Serenity Falls and many others. The Portage Escarpment leads to Ithaca falls.

F

Face

The vertical (or near vertical) surface of a cliff.

Fan

A type of horsetail waterfall that spreads horizontally, fanning out, considerably before hitting the base of the falls.

Finger Lake

The linear, north-to-south glacial lakes of upstate NY are some of the deepest in America. Early map-makers thought they resembled the fingers of a hand, and dubbed them the Finger Lakes. The longest is Cayuga. Seneca is the largest. There are 11 total: Otisco Lake, Skaneateles Lake, Owasco Lake, Cayuga Lake, Seneca Lake, Keuka Lake, Canandaigua Lake, Honeoye Lake, Canadice Lake, Hemlock Lake and Conesus Lake. Some other adjacent lakes (Cazenovia and Oneida Lakes to the east) are often considered to be part of the Finger Lakes as well.

Floodplain

Flatlands in the watershed of a body of water that have a history of and thus future potential for seasonal flooding.

Fossil

Fossils (from Latin fossus, literally “having been dug up”) are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. The totality of fossils and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils is called paleontology. (courtesy of wikipedia.org)

Friable

Easily broken apart or burrowed through.

G

GIS

Geographic Information Systems. A database format that links data tables to maps with the capacity to easily manipulate data geographically.

Gorge

A narrow, steep valley, ravine or canyon, walled by cliffs, often carved over time by water.

Glacier

A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. A glacier is formed by multi-year ice accretion in sloping terrain. Glacier ice is the largest reservoir of freshwater on Earth, and second only to oceans as the largest reservoir of total water. Glaciers can be found on every continent except Australia. Geologic features associated with glaciers include end, lateral, ground and medial moraines that form from glacially transported rocks and debris; U-shaped valleys and corries (cirques) at their heads, and the glacier fringe, which is the area where the glacier has recently melted into water. (courtesy of wikipedia.org)

Glen

A gorge.

Granite

Granite is a common and widely-occurring type of intrusive, felsic, igneous rock. Granites are usually a white or buff color and are medium to coarse grained, occasionally with some individual crystals larger than the groundmass forming a rock known as porphyry. Granites can be pink to dark gray or even black, depending on their chemistry and mineralogy. (courtesy of wikipedia.org)

Grist Mill

A mill where grain is ground into flour.

GPS

Global Positioning System. A technology that uses US military satellites to triangulate the position of a GPS receiver. Can also provide elevation data. Software, in conjunction with a GPS receiver can provide direction, speed and provide navigational data. GPS receivers can be accurate within 2 meters (6′).

Gulf

A gorge.

H

Hanging Valley

A hanging valley is a tributary valley with the floor at a higher relief than the main channel into which it flows. They are most commonly associated with glacial valleys when a tributary glacier flows into a glacier of larger volume. The main glacier erodes a deep U-shaped valley with nearly vertical sides while the tributary glacier, with a smaller volume of ice, makes a shallower U-shaped valley. Since the surfaces of the glaciers were originally at the same elevation, the shallower valley appears to be ‘hanging’ above the main valley. Often, if water is flowing through the upper glacial valley, a waterfall will form. (courtesy of wikipedia.org)

Horsetail

A type of waterfall that maintains some contact with the rock behind it. Usually thin.

J

Joint

A defined vertical rock fracture.

Jump

A type of waterfall that freefalls from the caprock to the base. Also known as a ledge or plunge, the bedrock behind the falls is eroded further than the stronger more resistant caprock, sometimes leading to a shallow cavern behind the falls.
The freefall portion of the waterfall.

K

Kame

An irregularly shaped hill or mound composed chiefly of poorly sorted sand and gravel deposited by a sub-glacial stream as an alluvial fan or delta. It can have an irregular shape. Kames are often associated with kettles. (courtesy of wikipedia.org)

Kettle

A depression, often filled with water – a kettle lake, in glacial moraine or outwash sediments. A kettle is formed when a large block of ice separated from a retreating (melting) glacier becomes buried by sediments. Later, when the buried ice block melts, the sediment above collapses and a depression is formed in the landscape. (courtesy of wikipedia.org) Bathtub of Mendon Ponds, Monroe County, is a notable glacial kettle.

Knickpoint

A location in the stream where there is a sharp change in the slope of the channel such as a waterfall (steep slope) or lake (no slope).

L

Ledge

A type of waterfall that freefalls from the caprock to the base. Also known as a plunge or jump, the bedrock behind the falls is eroded further than the stronger more resistant caprock, sometimes leading to a shallow cavern behind the falls.

Limestone

A sedimentary rock, consisting mostly of calcite, found is locations where prehistoric marine environments once existed. Limestone colors vary depending on composition. Pure limestone is white. Grey indicates clay impurities. While red is usually colored by iron oxide. Limestone layers are generally thicker than shale layers.

Lithification

The process in which sediments compact under pressure and start to form rock. Fluids are lost from the sediments as pressure tightens the space in between grains. Heat generated from the pressure contributes to the bonding of sediment. This process can take thousands of years.

M

Metamorphic rock

A type of rock that is the result of the transformation of a pre-existing rock type by heat and/or pressure. Examples of metamorphic rock: marble, slate, gneiss and schist.

Meromictic Lake

A lake in which the layers of water do not mix. Lakes and ponds usually turn over their waters as a result of seasonal temperature change. Meromictic lakes are either very deep and have steep sides or are highly saline at the bottom, preventing turn-over. These lakes generally have massive collections of undisturbed sediments at the bottom with very slow rates of decay.

Mouth

The outlet where the stream empties into a pond, lake or ocean.

N

Newborn falls

A relatively new falls, usually not well defined and always close to the main body of water they empty into. Because they have not been around for long, they have not eroded away the rock enough to recede further away from the gully they empty into.

O

Oligotrophic

An environment that offers little to sustain life. Skaneateles Lake is an oligotrophic Finger Lake.

Oncolite

A rare, spherical lime rock formed by blue-green algae growth on a pebble or shell core. Hard when wet, brittle when dry.

P

Plunge

A type of waterfall that freefalls from the caprock to the base. Also known as a ledge or jump, the bedrock behind the falls is eroded further than the stronger more resistant caprock, sometimes leading to a shallow cavern behind the falls.

Plunge Pool

A pool at the base of a falls. formed by the erosion of sediment stirred by the waterfall.

Pool

A section of a stream where the water is deep and slow moving.

Pothole

Smooth bowl-shapes ground into rock by small rocks and/or sand swirling in the current of a whirlpool or at the base of waterfalls.

Precambrian rock

Rock formed during the Proterozoic and the Archaean eras that formed the first continents. The oldest rock on Earth.

Punchbowl

A type of waterfall that descends in constricted form, into a pool at the base, rather than cascading over rocks at the base.

R

Rapids

A section of the stream where the current is above normal and rocks and debris create turbulence known as “whitewater.”

Ribbon

A waterfall much taller than it is wide.

Riffle

A section of a stream where the water is more turbulent, shallow and the flow is reduced. Identifiable by aerated water flow.

River

A large stream, usually used as a waterway.

Run

A section of a stream where the flow is smooth and uninterrupted.

S

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in earth’s crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, gray, and white. (courtesy of wikipedia.org)

Sediment

Sand, pebbles or any particulate matter carried and deposited by water flow.

Sedimentary rock

One of the three main rock groups (along with igneous and metamorphic rocks) and is formed in three main ways—by the deposition of the weathered remains of other rocks (known as clastic sedimentary rocks); by the deposition of the results of biogenic activity; and by precipitation from solution. Sedimentary rocks include common types such as chalk, limestone, sandstone, and shale.  (courtesy of wikipedia.org)

Segmented

Used to describe a waterfall that splits into 2 or more distinct drops.

Series

A group of waterfalls, usually separated by pools or sections of the stream. Sometimes one is not visible from another. Sometimes considered part of the same falls.

Shale

A type of sedimentary rock, usually grey, formed from mud or fined grain silt, deposited in thin, easily fractured and porous layers. Because of its ease of erosion and common presence, shale contributes greatly to the characteristic NY State waterfall look.

Staircase

A type of waterfall that flows in a series of consistent steps, resembling a staircase.

Stratigraphy

A branch of geology, studying rock and sediment layers.

Stratum

A layer of rock or soil, of the same composition, distinguishable (but not necessarily of different composition) from surrounding layers. Lower stratum are geologically older than those above (except in rare cases).  This is referred to as the Law of Superposition.

Stream

A body of water with a detectable current and confined within a bed. (Also referred to as a brook or creek).

Superfund

A federal law that budgets for the clean-up of highly contaminated areas. Prioritizing residential areas and sites where contamination can spread.

Superposition (Law of)

A principle of geology that states that rock and sediment layers are arranged in time sequence, with older layers on the bottom and more recent layers on the top. Geological activity can disrupt this order.

T

Talus

A pile a debris fallen from the cliff edge, usually forming a slope against the cliff face or waterfall.

Tiered

A type of waterfall that flowsin  a series of distinct steps or rock layers. A type of cascade with more distinct steps or jumps.  Also referred to as a staircase if the jumps resemble stairs.

Topographic map

A geographic map indicating elevation using contour lines. Commonly referred to as Topo maps. An excellent tool for locating waterfalls. There are several rules to note when viewing topographic maps:
The rule of Vs: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion.The rule of Os: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called “hachures”. Spacing of contours: close contours indicate a steep slope; distant contours, a shallow slope. Two or more contour lines merging indicate a cliff.  See our Topographic Maps section for more information.

Tributary

A stream that contributes to another. One that does not empty into an ocean or lake, but contributes to the flow of another stream or river (usually a larger more defined stream).

Turbidity

Water’s ability to hold particulates. Water of high turbidity is cloudy and considered dirty.

Turtle Stone

See concretion.

V

Valley

A valley is a landform, which can range from a few square miles (square kilometers) to hundreds or even thousands of square miles in area. It is typically a low-lying area of land, surrounded by higher areas such as mountains or hills. (courtesy of wikipedia.org)

W

Whirlpool

A section of a stream where the current flows in a circular path towards the center of the circle. In streams and rivers whirlpools can vary in size and strength. They are often found at the bottom of waterfalls on the fringe of pools or any location where fast-moving water is adjacent to slow-moving pools.

Watershed

The region surrounding a waterway from which it receives water. Also known as a drainage basin.

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