Ablation
The loss of ice and snow from a glacier system. This occurs through a variety of processes including melting and runoff, sublimation, evaporation, calving, and wind transportation of snow out of a glacier basin
Accumulation
The addition of ice and snow into a glacier system. This occurs through a variety of processes including precipitation, firnification, and wind transportation of snow into a glacier basin from an adjacent area.
Accumulation Area
The part of a glacier that is perennially covered with snow. Also called N�v�.
Advance
An increase in the length of a glacier compared to a previous point in time
Arete
A jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife
Barren Zone
An area of fresh, vegetation-free bedrock around the margin of a retreating glacier that documents the recent loss of ice
Bergshrund
A single large crevasse or series of sub-parallel crevasses that develop at the head of a glacier. The location where ice pulls away from the bedrock wall of the cirque against which it accumulated`
Bergy Seltzer
A crackling or sizzling similar to that made by soft drinks or seltzer water but louder. The sound made as air bubbles formed at many atmospheres of pressure are released during the melting of glacier ice
Braided Stream
A stream that is characterized by a complex network of branches that continuously separate and reunite. Streams braid when they have a much greater sediment load than they can carry
Calving
The process by which pieces of ice break away from the terminus of a glacier that ends in a body of water or from the edge of a floating ice shelf that ends in the ocean. Once they enter the water, the pieces are called icebergs
Calving Glaciers
A glacier with a terminus that ends in a body of water (river, lake, ocean) into which it calves icebergs
Chatter Marks
A series of small, closely spaced, crescentic grooves or scars formed in bedrock by rocks frozen in basal ice as they move along and chip the glacier's bed. The horns of the crescent generally point down glacier
Cirque
semi-circular bedrock feature created as glaciers erode back into a mountain; bowl-shaped, amphitheater-like depression eroded into the head or the side of a glacier valley
Cirque Glacier
A small glacier that forms within a cirque basin, generally high on the side of a mountain, does not extend beyond edge of cirque
Crescentic Gouges
Any curved mark or fracture produced by plucking or chipping of the glacier's bed. Larger than chatter marks,typically the horns of these gouges point up glacier
Crevasse
crack in upper 30 m of glacier
Debris Cone
A cone or mound of debris-covered ice, with a thick enough sediment cover to protect the ice from melting
Dendrochronology
The study of tree rings and subfossil wood to provide information about the glacial and climatic history of an area.
Disarticulation
process through which large blocks of ice, sometimes greater than .5 miles in width, detach from the thinning and retreating terminus of a glacier that ends in a body of water; like large scale calving
Distributary
A tongue of glacier ice that flows away from the main trunk of the glacier`
Downwasting
The thinning of a glacier due to the melting of ice. This loss of thickness may occur in both moving and stagnant ice
Drift
A collective term used to describe all types of glacier sedimentary deposits, regardless of the size or amount of sorting. The term includes all sediment that is transported by a glacier, whether it is deposited directly by a glacier or indirectly by runn
Drumlin
An elongated ridge of glacial sediment sculpted by ice moving over the bed of a glacier
Epoch
a division of time that is a subdivision of a period and is itself subdivided into ages, corresponding to a series in chronostratigraphy.
Erratic
A rock of unspecified shape and size, transported a significant distance from its origin by a glacier or iceberg and deposited by melting of the ice
Esker
A meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial or englacial stream channel
Eustacy
Fluctuations in the worldwide sea-level regime caused by changes in the quantity of seawater available. The greatest changes are caused by water being added to, or removed from, glaciers
Firn
An intermediate stage in the transformation of snow to glacier ice. Snow becomes firn when it has been compressed so that no pore space remains between flakes or crystals, a process that takes less than a year
Firn Line
A line across the glacier, from edge to edge, that marks the transition between exposed glacier ice and the snow-covered surface of a glacier
Fjord
A glacially eroded or modified U-shaped valley that extends below sea level and connects to the ocean. Filled with seawater, depths may reach more than 1,000 feet below sea leve
Foliation
The layering or banding that develops in a glacier during the process of transformation of snow to glacier ice
Fountain
A glacial spring, generally discharging supercooled water with a significant hydrostatic head
Glacial Groove/Glacial Furrow/Groove
A linear depression, inches to miles in length, produced by the removal of rock or sediment by the erosive action of a glacier; elongated depression carved out of bedrock as rock particles in base scour away underlying bedrock
Glacial Lake
An accumulation of standing liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier
Glacial Stream
A channelized accumulation of (moving) liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier, moving under the influence of gravity.
Glacier
A large, perennial accumulation of ice, snow, rock, sediment and liquid water originating on land and moving down slope under the influence of its own weight and gravity; a dynamic river of ice.
Glacier Cave
A cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves
Glacier Flow
The movement of ice in a glacier, typically in a downward and outward direction, caused by the force of gravity
Glacier Ice
A mono-mineralic type of rock, composed of crystals of the mineral ice, formed through metamorphism of snowflakes. Metamorphism results in recrystallization, increased density, and the growth of hexagonal crystals. This ice comprises the majority of the m
Glacier Table
A rock that is balanced on a pedestal of ice, and elevated above the surface of a glacier. The rock protects the pedestal of ice from melting by insulating it from the sun
Hanging Glacier
A glacier that originates high on the wall of a glacier valley and descends only part of the way to the surface of the main glacier. Avalanching and icefalls are the mechanisms for ice and snow transfer to the valley floor below.
Hanging Valley
valley carved out by small tributary glacier that joins w/valley carved out by much larger glacier
Holocene
The current part of geologic time. The Holocene epoch began ~12,000 years ago, at the end of the Pleistocene epoch
Horn
pyramid-shaped mountain peak created as multiple glaciers erode away at same mountain; A pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques
Ice Cap
A dome-shaped accumulation of glacier ice and perennial snow that completely covers a mountainous area or island, so that no peaks or Nunataks poke through
Ice Field
A continuous accumulation of snow and glacier ice that completely fills a mountain basin or covers a low-relief mountain plateau to a substantial depth. When the thickness become great enough, tongues of ice overflow the basins or plateaus as Valley Glaci
Ice Rafting
The transportation of glacier sediment away from the ice margin by icebergs
Ice Sheet
A thick, subcontinental to continental-scale accumulation of glacier ice and perennial snow that spreads from a center of accumulation, typically in all directions. Also called a Continental Glacier
Ice Shelf
The floating terminus of a glacier, typically formed when a terrestrial glacier flow into a deep water basin, such as in Antarctica and the Canadian Arctic
Iceberg
A block of ice that has broken or calved from the face of a glacier and is floating in a body of marine of fresh water
Ice-Dammed Lake
A lake that exists because its water is restricted from flowing by an ice dam
Ice Fall
Part of a glacier where the ice flows over a bed with a very steep gradient, typically at a higher rate than both above and below. As a result the surface is fractured and heavily crevassed. In a river system, this would be a waterfall; ice equivalent of
Ice-Marginal Lake
A lake that is located adjacent to the terminus of a glacier. Typically, these lakes form in bedrock basins scoured by the glacier. They enlarge as the glacier retreats. Sometimes they are dammed by an End or Recessional Moraine
Isostasy
The balance between changes within the Earth's crust and mantle, where material is displaced in response to an increase (isostatic depression) or decrease (isostatic rebound) in mass at any point on the Earth's surface above. Such changes are frequently c
J�kulhlaup
A glacier outburst flood resulting from the failure of a glacier-ice-dam, glacier-sediment-dam, or from the melting of glacier ice by a volcanic eruption
Kame
A sand and gravel deposit formed by running water on stagnant or moving-glacier ice
Kettle
A depression that forms in an outwash plain or other glacial deposit by the melting of an in-situ block of glacier ice that was separated from the retreating glacier-margin and subsequently buried by glacier sedimentation. As the buried ice melts, the dep
Little Ice Age (Neoglaciation)
The most recent interval of temperate glacier expansion and advance on Earth. It began ~650 years ago and continued into the 20th century in many locations. Temperate glaciers in North America, South America, Africa, Europe, and Asia were affected
Mass Balance
A measure of the change in mass of a glacier at a certain point for a specific period of time. The balance between accumulation and ablation
Moraine
accumulation of unsorted, unconsolidated material deposited by glacial ice (till) w/no layering
Ablation Moriane
An irregular-shaped layer or pile of glacier sediment formed by the melting of a block of stagnant ice. Ultimately, ablationa moraine is deposited on the former bed of the glacier. Also called Ablation Till
Ground Moraine
till deposited under glacier; located behind end moraines
Ice-Cored Moraine
A moraine ridge consisting of a drape of sediment overlying a mass of stagnant ice
Lateral Moraine
till deposited along sides of alpine glacier
Medial Moraine
till deposited on top and middle of existing glacier
Push Moraine
A ridge or pile of unstratified glacial sediment that is formed in front of the ice margin by the terminus of an advancing glacier, bulldozing sediment in its path; only formed by glaciers that have retreated and then advance again
Recessional Moraine
A ridge of glacial sediment that forms when the terminus of a retreating glacier remains at or near a single location for a period of time sufficient for a cross-valley accumulation to form
Terminal Moraine/End Moraine
A cross-valley, ridge-like accumulation of glacial sediment that forms at the farthest point reached by the terminus of an advancing glacier; accumulation of till at terminus or snout of glacier
Moulin (Glacier Mill)
A narrow, tubular chute or crevasse through which water enters a glacier from the surface
Nunatak
A mountain peak or ridge that pokes through the surface of an Ice Field or a Glacier. It may separate adjacent Valley Glaciers
Ogives
An arcuate, convex, down-glacier-pointing band or undulation that forms on the surface of a glacier at the base of an icefall. Two types of ogives occur: wave ogives, which are undulations of varying height and band ogives, which are alternating light- an
Outwash Plain
A broad, low-slope angle alluvial plain composed of glacially eroded, sorted sediment (termed outwash), that has been transported by meltwater. The alluvial plain begins at the foot of a glacier and may extend for miles. Typically, the sediment becomes fi
Piedmont Glacier
A fan or lobe-shaped glacier, located at the front of a mountain range. It forms when one or more valley glaciers flow from a confined valley onto a plain where it expands
Polar Glacier
A glacier with a thermal or temperature regime in which ice temperatures always remain below the freezing point
Pit Pond
A depression in an outwash plain by the melting of a block of ice floated to its depositional site by meltwater and subsequently buried by sediment. As it melts, a depression in the surface of the outwash plain develops
Pleistocene
The epoch of geologic time, informally called the 'The Great Ice Age' or the 'Glacial Epoch', that began ~1.8 million years ago and ended ~8,000 years ago (see the CVO's Geologic Time Scale). During this interval continental glaciers repeatedly formed and
Plucking
The mechanical removal of pieces of rock from a bedrock face that is in contact with glacier ice. Blocks are quarried and prepared for removal by the freezing and thawing of water in cracks, joints, and fractures. The resulting pieces are frozen into the
Reconstituted Glacier
A glacier formed below the terminus of a hanging glacier by the accumulation, and reconstitution by pressure melting (regelation), of ice blocks that have fallen and/or avalanched from the terminus of the hanging glacier. Also called Glacier Remani�
Remnant
An isolated melting mass of glacier ice, that has become detached from its source and the remainder of the glacier
Retreat
A decrease in the length of a glacier compared to a previous point in time. As ice in a glacier is always moving forward, its terminus retreats when more ice is lost at the terminus to melting and/or calving than reaches the terminus. During retreat, ice
Roche Moutonnee
An elongated, rounded, asymmetrical, bedrock knob produced by glacier erosion. It has a gentle slope on its up-glacier side and a steep- to vertical-face on the down-glacier side
Rock Glacier
A glacier-like landform that often heads in a cirque and consists of a valley-filling accumulation of angular rock blocks. Rock glaciers have little or no visible ice at the surface. Ice may fill the spaces between rock blocks. Some rock glaciers move, al
Rock Flour
Fine-grained, silt-size sediment formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice. When it enters a stream, it turns the stream's color brown, gray, iridescent blue-green, or milky white. Also called Glacier Flo
S�rac
A jagged pinnacle or tower of glacier ice located on the surface of a glacier, formed as a glacier flows down an icefall or by the intersection of crevasses. Frequently, large areas of a glacier will be covered by s�racs
Snowbridge
A mass of snow that has accumulated in the top of an open crevasse, masking the existence of the crevasse. Frequently, a large void exists below the snowbridge
Stagnation
The in-situ melting of glacier ice. Many glaciers have stagnant termini, covered by thick sediment debris. Some support vegetation, including mature forests
Striations
lines etched in bedrock as individual particles embedded in ice at base scratch underlying bedrock; indicate orientation of flow; Multiple, generally parallel, linear grooves, carved by rocks frozen in the bed of a glacier into the bedrock over which it f
Suncups
A series of bowl-like depression melted into a snow or ice surface, separated by a network of connected ridges. Individual suncups may be more than three feet deep and ten feet in diameter. Suncups form during warm, sunny conditions
Surge
A short-lived, frequently large-scale, increase in the rate of movement of the ice within a glacier. Ice velocities may increase 10 to 100 times above normal flow rates. In some surges, the terminus of a glacier rapidly advances. Although not all glaciers
Tarn
glacial lake produced by abrasion and plucking of bedrock on bottom of cirque; lake that develops in the basin of a cirque, generally after the melting of the glacier
Temperate Glacier
A glacier with a or temperature-regime in which liquid water coexists with frozen water (glacier ice) during part or even all of the year
Terminus
The lower-most margin, end, or extremity of a glacier. Also called Toe, End or Snout
Tidewater Glacier
A glacier with a terminus that ends in a body of water influenced by tides, such as the ocean or a large lake. Typically, tidewater glaciers calve ice to produce icebergs
Till
unsorted and unstratified accumulation of glacial sediment, deposited directly by glacier ice. Till is a heterogeneous mixture of different sized material deposited by moving ice (lodgement till) or by the melting in-place of stagnant ice (ablation till).
Trimline
A clear boundary line on the wall of a glacier valley that delineates the maximum recent thickness of a glacier. It may be a change in the color of the bedrock, indicating the separation of weathered from unweathered bedrock; the limit of a former lateral
U-Shaped Valley
A valley with a parabolic or "U" shaped cross-section, steep walls and generally a broad and flat floor. Formed by glacier erosion, a U-shaped valley results when a glacier widens and over-steepens a V-shaped stream valley
Valley Glacier
A glacier that flows for all or most of its length within the walls of a mountain valley. Also called an Alpine Glacier or a Mountain Glacier
Varve
a pair of sedimentary layers, a couplet, that form in an annual cycle as the result of seasonal weather changes. Typically formed in glacial lakes a varve couplet consists of a coarser grained summer layer formed during open-water conditions, and a finer
The 5 Known Ice Ages
From most recent to least : Quarternary (Pleistocene), Karoo, Andrean-Saharan, Cryogenian (Sturtian-Varangian), and Huronian
Glacial and Interglacial periods in Quarternary Ice Age
Most recent to least : Flandrian (interglacial), W�rm/Wisconsin/Weichselian (glacial), Riss-W�rm/Sangamonian (interglacial), Riss/Illinoian (glacial), Mindel-Riss/Pre-Illinoian (interglacial), Mindel/Pre-Illinoian (glacial), G�nz-Mindel/Pre-Illinoian (int
Milankovitch Cycles
The episodic nature of the Earth's glacial and interglacial periods within the present Ice Age (the last couple of million years) have been caused primarily by cyclical changes in the Earth's circumnavigation of the Sun. Variations in the Earth's eccentri
Eccentricity
1st of the Milankovitch Cycles. the shape of Earth's orbit around the sun, changes from more to less elliptical over a period of 100,00 years. This alters the the distance the Earth is from the Sun, resulting in reducing or increasing the amount of radiat
Axial Tilt
2nd cycle of Milankovitch Cycles. the inclination of the Earth's axis in relation to its plane of orbit around the Sun, oscillations occur over a period of 41,000 years, varies between 21.5 degrees to 24.5 degrees
Precession
3rd and final stage of Milankovitch Cycles. the slow wobble of the Earth as it spins on its axis. Periodicity of 23,000 years. Results in greater season contrasts