Untitled Flashcards Set

·Alpine Glacier

See valley glacier below.

·Calving Glacier

A glacier with a terminus that ends in a body of water (river, lake, ocean) into which it calves icebergs. 

·Cirque glacier

A small glacier that forms within a cirque basin, generally high on the side of a mountain. often with lake

·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. 

·Ice Apron

Accumulations of snow and Ice masses that stick to the topography of the glacierized basin. (Rock Faces covered in ice)

·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 Glaciers. 

·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. One of the two main types of glaciers.

·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. The 30-mile wide Malaspina is the largest in Alaska. 

·Polar Glacier

A glacier with a thermal or temperature regime in which ice temperatures always remain below the freezing point. 

·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 Remaniè.

·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, although very slowly. 

·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. 

·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. think ice wall

·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. One of the two main types of glaciers.
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A

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. Ablation Zone.Retreat.

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 Névé. This is where the snow falls, and is the part with the highest elevation.

Advance

An increase in the length of a glacier compared to a previous point in time. As ice in a glacier is always moving forward, a glacier's terminus advances when less ice is lost due to melting and/or calving than the amount of yearly advance.

Albedo

The proportion of the incident light or radiation that is reflected by a surface, typically that of a planet or moon.

Altimetry

A technique for measuring the height of water and ice surfaces, commonly used in the ocean.

Amundsen Sea Embayment

This is a sea in western Antarctica that has contributed to around 40% of sea level rise. 

Antarctic Circumpolar Current (ACC)

This is an ocean current that flows clockwise around Antarctica, it could also be called the West Wind Drift.

Arete

A jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife. A French term referring to the bones in a fish backbone.
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B

Barren Zone

An area of fresh, vegetation-free bedrock around the margin of a retreating glacier that documents the recent loss of ice.

Basal sliding

Basal sliding is the act of glacier sliding over the bed due to meltwater under the ice acting as a lubricant.

Beaufort Gyre

An ocean and ice circulation pattern in the Beaufort Sea, north of Alaska. This gyre moves in a clockwise direction, fed by an average high-pressure system that fosters anti-cyclonic winds. Ice that forms in or drifts into the Beaufort Gyre has historically remained in the Arctic ice system for years, accumulating snow and thickening each winter. Beginning in the late 1990s, the ice began melting away while in the southern parts of the gyre, before completing the circulation.

Bed deformation

The deformation of the glacial bed that leads to glacial sliding, it is one of the three main ways that glacial sliding occurs.

Bergschrund

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. In winter, the crevasse fills with snow. In spring or summer, it reopens. (Originally a German term).

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. Also called Ice Sizzle. 

Braided Stream (Anastomizing 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. Also called an Anastomosing Stream/.
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C

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.

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

A bowl-shaped, amphitheater-like depression eroded into the head or the side of a glacier valley. Typically, a cirque has a lip at its lower end. The term is French and is derived from the Latin word circus.

Continentality

Continentality refers to the climate affect where large landmasses experience more extreme temperature variations than coastal areas due to the thermal properties of water versus land. In areas with high Continentality, winters can be much colder, which enhances the development of permafrost and periglacial conditions. This is especially true in places like Siberia and Alaska, where vast land masses experience very cold winters.

Crescentic Gouge

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. Also called Lunate Fracture or Crescentic Mark. 

Cryoconite

Dust that is found on the surface of a glacier (such as the Greenland ice cap) especially on the bottom of small depressions and is formed as a result of differential melting of the ice.

Crevasse

A crack or series of cracks that open in the surface of a moving glacier in response to differential stresses caused by glacier flow. They range in shape from linear to arcuate, in length from feet to miles. Their orientation may be in any direction with respect to the glacier flow. The deepest crevasses may exceed 100 feet.

Types of Crevasses:

Bergschrunds

Form at the beginning of the glacier where the glacier pulls away from the rock wall at its head.

Longitudinal/splay Crevasses

Form in the direction of a glacier flow, and where ice slowly spreads out sideways to cover a larger area. Commonly found near the terminus of glaciers (glacier termini).

Marginal/shear Crevasses

Form near the side. Marginal crevasses are caused by shear between the valley wall and the glacier (because the ice in the middle of the glacier flows faster. They form a herring- bone pattern, pointing about 45° up-glacier from the valley wall.

Transverse Crevasses

Form across a glacier in a region where the speed is increasing, which causes stretching (tensile stress) in the direction of glacier flow. They fan across the glacier. They are common in the accumulation zone and near steepening slopes, such as an ice fall.

Radial Crevasses

Form where a glacier turns a corner. The ice on the outside of the bend has to travel faster than the ice on the inside corner. This tension pulls the ice farther out from the corner, creating crevasses which radiate out from the inside wall.
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D

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

Disarticulation is the 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. Disarticulation occurs as the terminus thins to where its buoyandcy no longer permits it to remain in contact with its bed. As the glacier begins to float free and rises off the bottom it rapidly comes apart along old fracture scars and crevasses. For example, at Bering Glacier, in the Chugach Mountains, Alaska, a single observed disarticulation event resulted in nearly 2/3 of a mile of terminus retreat in a single day. As many as 100 discrete, tabular pieces of glacier ice have been observed separating from the glacier's terminus in a single event. Bering Glacier flows through Wrangell-St. Elias National Park, Alaska.

Distributary

A tongue of glacier ice that flows away from the main trunk of the glacier. This may result from differential melting changing the gradient of part of a 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. Also called Thinning.

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 running water that originates from a glacier.

Driftless Area/Paleozoic Plateau

An area in the widwest that was untouched by glaciers, it consists of southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme northwestern corner of Illinois.

Drake Passage 

The Drake passage is the separation of South America and Antarctica that formed 30 million years ago.

Drumlin

An elongated ridge of glacial sediment sculpted by ice moving over the bed of a glacier. Generally, the down-glacier end is oval or rounded and the up-glacier end tapers. The shape is often compared to an inverted, blunt-ended canoe, or teardrop shaped hills. Although not common in Alaska, drumlins cover parts of the Eastern and Midwestern United States (Irish). The steepest side of a drumlin points in the direction upstream of ice flow.
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E

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. Erratics range from pebble-size to larger than a house and usually are of a different composition that the bedrock or sediment on which they are deposited.

ELA

This stands for Equilibrium Line Altitude, and it marks tha area or zone on a glacier where accumulation is balance by ablation over a 1-year period.

Esker

A meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial or englacial stream channel. Its floor can be bedrock, sediment, or ice. Subsequent melting of the glacier exposes the deposit. Generally composed of stratified sand and gravel, eskers can range from feet to miles in length and may exceed 100 feet in height.

EOT (Eocene Oligocene Transition)

This was a mass extinction event, and the earth transitioned from a greenhouse climate to an icehouse climate. The oceans shrunk, ice grew.

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.
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F

Floe (ice floe): An ice floe (/floÊŠ/) is a large pack of floating ice often defined as a flat piece at least 20 m across at its widest point, and up to more than 10 km across.[1] Drift ice is a floating field of sea ice composed of several ice floe

First Glaciation Period

This was the Huronian, which was 2.4 to 2.1 billion years ago during the early protozoan Eon.

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. This is 7/8s as dense as water.

Firn line

A line across the glacier, from edge to edge, that marks the transition between exposed glacier ice (below) and the snow-covered surface of a glacier (right). During the summer melt season, this line migrates up-glacier. At the end of the melt season the firn line separates the accumulation zone from the ablation zone.

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 level. The largest Alaskan fiords are more than 100 miles long and more than 5 miles wide. Also spelled Fiord.

Foliation

The layering or banding that develops in a glacier during the process of transformation of snow to glacier ice. Individual layers, called folia, are visible because of differences in crystal or grain size, alternation of clear ice and bubbly ice, or because of entrained sediment.

Fountain

A glacial spring, generally discharging supercooled water with a significant hydrostatic head.

Frazil Ice

Soft or amorphous ice formed by the accumulation of ice crystals in water that is to turbulent to freeze solid. The ice crystals can have diameters of a few millimeters. These crystals are needle like (think satisfying ticktock water).
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G

Glacial flooding

A glacier-dammed outburst flood may be called GLOF or jökulhlaups. Glacial activity is thought to be the cause o Fanny of the largest flooding events in history.

Glacial Formation

A glacier forms when snow accumulates over time, turns to ice, and begins to flow outwards and downwards under the pressure of its own weight.

Glacial Flow

Glaciers flow by basal sliding, internal deformation, and Bed deformation.

Glacial Growth

Glacial growth is most impacted by temperature, precipitation, and sun exposure.

Glacial Groove/Glacial Furrow

A linear depression, inches to miles in length, produced by the removal of rock or sediment by the erosive action of a glacier.

Glacial Lake

An accumulation of standing liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier. Tarns, Finger lakes, and Paternoster lakes are all types of glacial lakes.

Glacial Requirements

Ice must achieve critical mass and be able to flow, AND must be able to last through the summer.

Glacial Stream 

A channelized accumulation of 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. Glaciers are classified by their size, location, and thermal regime.

Glacier Cave 

A cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves. Also called Ice Cave.

Glacier Flow 

The movement of ice in a glacier, typically in a downward and outward direction, caused by the force of gravity. 'Normal' flow rates are in feet per day. 'Rapid' flow rates (i.e. surge) are in 10s or 100s of feet per day.

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 not snow crystals! This ice comprises the majority of the mass of a glacier. Intermediate stages include Firn and Neve. This covers~10% of earth. This ice is very very dense, much denser than freezer ice. It is only glacial ice when under 20% air.

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.

Gravimetry

The use of a gravimeter to measure the force of gravity depending on the distance from the earth's core. There is an accelerometer in the gravimeter that does this. Using this, detailed maps can be created judging off the force of gravity. (See Gravimetry map in picture doc)

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H

Hanging Valley

A former tributary glacier valley that is incised into the upper part of a U-shaped glacier valley, higher than the floor of the main valley. Hanging valley streams often enter the main valley as waterfalls.

Holocene

The current part of geologic time. The Holocene epoch began ~12,000 years ago, at the end of the Pleistocene epoch.

Horn

A pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques. Headward erosion has cut prominent faces and ridges into the peak. When a peak has four symmetrical faces, it is called a Matterhorn.
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I

Ice Ages 

An ice age is a long period of time with widespread glaciation. Scientists have recorded five significant ice ages throughout the Earth's history: the Huronian (2.4-2.1 billion years ago), Cryogenian (850-635 million years ago), Andean-Saharan (460-430 mya), Karoo (360-260 mya) and Quaternary (2.6 mya-present).

Ice Rafting

The transportation of glacier sediment away from the ice margin by icebergs. Sediment transported by floating ice and deposited in the ocean is called glacial-marine sediment. Deposited in lakes, it is called glacial-lacustrine sediment.

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. Alaskan icebergs rarely exceed 500 feet in maximum dimension. In order of increasing size, the following names are used: Brash Ice, Growler, Bergy Bit.

Tabular Iceberg

These icebergs have steep sides and a flat top. They have a minimum height to width ratio of 1 to 6. They are some of the largest icebergs in the world.

Non Tabular Iceberg

These are dry dock icebergs, blocky icebergs, and wedge icebergs.

Ice Cores

These are cylinders of ice that are drilled from the ground that show history in layers. These are great to show volcanic eruptions.

Ice-Dammed Lake

A lake that exists because its water is restricted from flowing by an ice dam. Sometimes these lakes form because an advancing glacier had blocked a valley.

Icefall

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-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.

Internal Deformation

Internal deformation occurs predominantly in cold glaciers where gravity and the pressure of ice in the accumulation zone causes ice crystals to slide over each other in a series of parallel planes in a 'crumpling' deformation.

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 caused by advances or retreats of glaciers.
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J-L

Jökulhlaup

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 (Icelandic).

Kame

A sand and gravel deposit formed by running water on stagnant or moving-glacier ice. Crevasse fills or crevasse ridges form within crevasses. Kames form on flat or inclined ice, in holes, or in cracks. A kame terrace forms between the glacier and the adjacent land surface. Shapes include hills, mounds, knobs, hummocks, or ridges.

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 depression enlarges. Kettles often become bogs or peat lands.

Laurentide ice sheet

This was an ice sheet in the most recent ice age, that covers modern day Canada and the northern United States (including northern Indiana). This was the ice sheet that made the Great Lakes.

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.
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M

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. Also called Mass Budget.

Milankovitch

 28 May 1879- 12 December 1958 He was a Serbian mathematician, astronomer, climatologist, geophysicist, civil engineer, and popularizer of science. Primarily known for his Milankovitch Cycles.

Milankovitch Cycles

Small cyclical variations in the shape of Earth's orbit, its wobble and the angle its axis is tilted play key roles in influencing Earth's climate over timespans of tens of thousands to hundreds of thousands of years. This causes Ice-Ages.

The three factors are 

1. The shape of Earth’s orbit, known as eccentricity;

2. The angle Earth’s axis is tilted with respect to Earth’s orbital plane, known as obliquity; and

3. The direction Earth’s axis of rotation is pointed, known as precession.

Moraine

A general term for unstratified and unsorted deposits of sediment that form through the direct action of, or contact with, glacier ice. Many different varieties are recognized on the basis of their position with respect to a glacier. Often described as bands.

·Ablation Moraine 

An irregular-shaped layer or pile of glacier sediment formed by the melting of a block of stagnant ice. Ultimately, ablation moraine is deposited on the former bed of the glacier. Also called Ablation Till.

·Ground Moraine

A blanket of glacier till deposited on all of the surfaces over which a glacier moves, typically by moving ice.

·Ice-cored Moraine

A moraine ridge consisting of a drape of sediment overlying a mass of stagnant ice.

·Lateral Moraine

A sediment ridge, located on a glacier's surface adjacent to the valley walls, extending down glacier to the terminus. It forms by the accumulation of rock material falling onto the glacier from the valley wall, rather than by water deposition. When snow grains grow larger lateral Moraines get smaller.

·Medial Moraine

A sediment ridge, located on a glacier's exposed ice surface, away from its valley walls, extending down glacier to the terminus. It forms by the joining of two lateral moraines when two glaciers merge.

·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.

·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

A cross-valley, ridge-like accumulation of glacial sediment that forms at the farthest point reached by the terminus of an advancing glacier. Also called an End Moraine.

Milankovitch cycles

Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years.

Moulin (Glacier Mill)

A narrow, tubular chute or crevasse through which water enters a glacier from the surface. Occasionally, the lower end of a moulin may be exposed in the face of a glacier or at the edge of a stagnant block of ice.
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N-O

Net Mass Balance

Accumulation-Ablation

Neve

The first year of glacial snow, it is hard and granular, the result of partial melting, re-freezing, and compacting, it forms the surface part of the upper end of a glacier.

Nunatak

A mountain peak or ridge that pokes through the surface of an Ice Field or a Glacier. It may separate adjacent Valley Glaciers (Greenlandic).

Ogive

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- and dark-colored bands. These correspond to a glacier’s seasonal motion.

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 finer grained with increasing distance from the glacier terminus.

Optical Imagery

Satellites collect data through active or passive collection, active; where they emit radiation and measure the wave to make an image. Passive Sattelites measure preexisting waves.
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P

Paleozoic Glaciation

Paleozoic Ice Age (LPIA) and this glaciation is known as the Late Paleozoic Glaciation or Gondwana(n) Glaciation. The LPIA was the longest, most severe, and most widespread icehouse interval of the Phanerozoic. It consisted of multiple, million year-scale glacial episodes that alternated with interglacial/nonglacial conditions of approximately the same duration. Atmospheric CO2 is estimated to have reached the lowest levels and O2 the highest levels of the Phanerozoic. The three supercontinents during this age were the Laurentia, Baltic, and the Gondwana.

Periglaciation 

This is the edges of glacial areas, and this describes the geomorphic processes that result from seasonal thawing and freezing, often in areas with permafrost. Continental it’s affects the extents of periglacion.

Pingos

Pingos are intrapermafrost ice-cored hills, 3–70 m (10–230 ft) high and 30–1,000 m (98–3,281 ft) in diameter.[1] They are typically conical in shape and grow and persist only in permafrost environments, such as the Arctic and subarctic. They are periglacial landforms.

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 covered significant parts of the Earth's surface. Together, the Holocene and Pleistocene epochs comprise the Quaternary Period.

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 glacier ice and transported. This is man made not erosional.

pressure ridge:

a ridge produced on floating ice by buckling or crushing under lateral pressure of wind or tide or on a congealing lava flow by the continued movement of its liquid interior

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Q-R

Radar

Ground penetrating radars send pulses through the ground to measure surfaces and caves and landforms. Kind of like echolocation.

randkluft

: a chasm formed when ice recedes from a mountainside or breaks away from stationary ice

Regelation

Regulation refers to the process where ice melts under pressure and then refreezes when the pressure is reduced. This process typically occurs at the base of a glacier, where the pressure from the overlying ice causes melting. As the ice moves and pressure is relieved, the water refreezes, helping the glacier to flow and move. This process is especially important in the movement of glaciers over uneven terrain.

Remnant

An isolated melting mass of glacier ice, that has become detached from its source and the remainder of the glacier. Some remnants cover many square miles.

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 in a glacier does not move back up the valley.

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.

Rockslide

Several landslides generated by the Great Alaskan Earthquake, Good Friday 1964, fell onto the surface of the so-named glacierin the Chugach Mountains, Alaska.

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 Flour or Glacier Milk.
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S

Sérac

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 séracs.

Seabed Gouging

Seabed gouging by ice is a process that occurs when floating ice features (typically icebergs and sea ice ridges) drift into shallower areas and their keel comes into contact with the seabed. As they keep drifting, they produce long, narrow furrows most often called gouges, or scours. SEE DIAGRAM

Snow: when new layers of snow bury and compress previous layers the snow re-crystallizes into grains the same size and shape as sugar. When snow grains grow larger lateral Moraines get smaller. When snow accumulates it turns into ice.

Snowball Earth events

The two hypothesized snowball earth events were the Sturtian and Marinoan glaciations.

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.

Seismology

The study of movement of materials on earth, such as a volcanic eruption, landslide, or explosion. The waves these movements emit can be used to find the depth of landforms, such as a cave or iceberg.

Striations

Multiple, generally parallel, linear grooves, carved by rocks frozen in the bed of a glacier into the bedrock over which it flows.

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. They may form hexagonal patterns. They are NOT evenly spaced.

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 surge, those that do often surge with some sort of a periodicity.
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T-Z

Tarn

A lake that develops in the basin of a cirque, generally after the melting of the glacier.

Terminus 

The lowermost margin, end, or extremity of a glacier. Also called Toe, End or Snout.

Till (glacial till)

An 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/ accumulation till) or by the melting in-place of stagnant ice (ablation till). After deposition, some tills are reworked by water.

Tillites/Lithified tills

These are sedimentary rocks formed by the lithification of glacial tills.

Till Plain

Till plains are an extensive flat plain of glacial till that forms when a sheet of ice becomes detached from the main body of a glacier and melts in place, depositing the sediments it carries. Till plains have poorly sorted sediment and are formed by the glacier’s direct action, these differentiate till planes from outwash plains.

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 moraine or other sediment deposit; or the boundary between vegetated and bare bedrock.

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.

Varve

A varve is 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 grained winter layer formed from deposition from suspension during a period of winter ice cover. Many varve deposits contain hundreds of couplets. 

·Alpine Glacier

See valley glacier below.

·Calving Glacier

A glacier with a terminus that ends in a body of water (river, lake, ocean) into which it calves icebergs. 

·Cirque glacier

A small glacier that forms within a cirque basin, generally high on the side of a mountain. often with lake

·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. 

·Ice Apron

Accumulations of snow and Ice masses that stick to the topography of the glacierized basin. (Rock Faces covered in ice)

·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 Glaciers. 

·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. One of the two main types of glaciers.

·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. The 30-mile wide Malaspina is the largest in Alaska. 

·Polar Glacier

A glacier with a thermal or temperature regime in which ice temperatures always remain below the freezing point. 

·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 Remaniè.

·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, although very slowly. 

·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. 

·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. think ice wall

·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. One of the two main types of glaciers.
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A

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. Ablation Zone.Retreat.

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 Névé. This is where the snow falls, and is the part with the highest elevation.

Advance

An increase in the length of a glacier compared to a previous point in time. As ice in a glacier is always moving forward, a glacier's terminus advances when less ice is lost due to melting and/or calving than the amount of yearly advance.

Albedo

The proportion of the incident light or radiation that is reflected by a surface, typically that of a planet or moon.

Altimetry

A technique for measuring the height of water and ice surfaces, commonly used in the ocean.

Amundsen Sea Embayment

This is a sea in western Antarctica that has contributed to around 40% of sea level rise. 

Antarctic Circumpolar Current (ACC)

This is an ocean current that flows clockwise around Antarctica, it could also be called the West Wind Drift.

Arete

A jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife. A French term referring to the bones in a fish backbone.
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B

Barren Zone

An area of fresh, vegetation-free bedrock around the margin of a retreating glacier that documents the recent loss of ice.

Basal sliding

Basal sliding is the act of glacier sliding over the bed due to meltwater under the ice acting as a lubricant.

Beaufort Gyre

An ocean and ice circulation pattern in the Beaufort Sea, north of Alaska. This gyre moves in a clockwise direction, fed by an average high-pressure system that fosters anti-cyclonic winds. Ice that forms in or drifts into the Beaufort Gyre has historically remained in the Arctic ice system for years, accumulating snow and thickening each winter. Beginning in the late 1990s, the ice began melting away while in the southern parts of the gyre, before completing the circulation.

Bed deformation

The deformation of the glacial bed that leads to glacial sliding, it is one of the three main ways that glacial sliding occurs.

Bergschrund

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. In winter, the crevasse fills with snow. In spring or summer, it reopens. (Originally a German term).

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. Also called Ice Sizzle. 

Braided Stream (Anastomizing 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. Also called an Anastomosing Stream/.
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C

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.

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

A bowl-shaped, amphitheater-like depression eroded into the head or the side of a glacier valley. Typically, a cirque has a lip at its lower end. The term is French and is derived from the Latin word circus.

Continentality

Continentality refers to the climate affect where large landmasses experience more extreme temperature variations than coastal areas due to the thermal properties of water versus land. In areas with high Continentality, winters can be much colder, which enhances the development of permafrost and periglacial conditions. This is especially true in places like Siberia and Alaska, where vast land masses experience very cold winters.

Crescentic Gouge

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. Also called Lunate Fracture or Crescentic Mark. 

Cryoconite

Dust that is found on the surface of a glacier (such as the Greenland ice cap) especially on the bottom of small depressions and is formed as a result of differential melting of the ice.

Crevasse

A crack or series of cracks that open in the surface of a moving glacier in response to differential stresses caused by glacier flow. They range in shape from linear to arcuate, in length from feet to miles. Their orientation may be in any direction with respect to the glacier flow. The deepest crevasses may exceed 100 feet.

Types of Crevasses:

Bergschrunds

Form at the beginning of the glacier where the glacier pulls away from the rock wall at its head.

Longitudinal/splay Crevasses

Form in the direction of a glacier flow, and where ice slowly spreads out sideways to cover a larger area. Commonly found near the terminus of glaciers (glacier termini).

Marginal/shear Crevasses

Form near the side. Marginal crevasses are caused by shear between the valley wall and the glacier (because the ice in the middle of the glacier flows faster. They form a herring- bone pattern, pointing about 45° up-glacier from the valley wall.

Transverse Crevasses

Form across a glacier in a region where the speed is increasing, which causes stretching (tensile stress) in the direction of glacier flow. They fan across the glacier. They are common in the accumulation zone and near steepening slopes, such as an ice fall.

Radial Crevasses

Form where a glacier turns a corner. The ice on the outside of the bend has to travel faster than the ice on the inside corner. This tension pulls the ice farther out from the corner, creating crevasses which radiate out from the inside wall.
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D

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

Disarticulation is the 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. Disarticulation occurs as the terminus thins to where its buoyandcy no longer permits it to remain in contact with its bed. As the glacier begins to float free and rises off the bottom it rapidly comes apart along old fracture scars and crevasses. For example, at Bering Glacier, in the Chugach Mountains, Alaska, a single observed disarticulation event resulted in nearly 2/3 of a mile of terminus retreat in a single day. As many as 100 discrete, tabular pieces of glacier ice have been observed separating from the glacier's terminus in a single event. Bering Glacier flows through Wrangell-St. Elias National Park, Alaska.

Distributary

A tongue of glacier ice that flows away from the main trunk of the glacier. This may result from differential melting changing the gradient of part of a 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. Also called Thinning.

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 running water that originates from a glacier.

Driftless Area/Paleozoic Plateau

An area in the widwest that was untouched by glaciers, it consists of southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme northwestern corner of Illinois.

Drake Passage 

The Drake passage is the separation of South America and Antarctica that formed 30 million years ago.

Drumlin

An elongated ridge of glacial sediment sculpted by ice moving over the bed of a glacier. Generally, the down-glacier end is oval or rounded and the up-glacier end tapers. The shape is often compared to an inverted, blunt-ended canoe, or teardrop shaped hills. Although not common in Alaska, drumlins cover parts of the Eastern and Midwestern United States (Irish). The steepest side of a drumlin points in the direction upstream of ice flow.
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E

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. Erratics range from pebble-size to larger than a house and usually are of a different composition that the bedrock or sediment on which they are deposited.

ELA

This stands for Equilibrium Line Altitude, and it marks tha area or zone on a glacier where accumulation is balance by ablation over a 1-year period.

Esker

A meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial or englacial stream channel. Its floor can be bedrock, sediment, or ice. Subsequent melting of the glacier exposes the deposit. Generally composed of stratified sand and gravel, eskers can range from feet to miles in length and may exceed 100 feet in height.

EOT (Eocene Oligocene Transition)

This was a mass extinction event, and the earth transitioned from a greenhouse climate to an icehouse climate. The oceans shrunk, ice grew.

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.
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F

Floe (ice floe): An ice floe (/floÊŠ/) is a large pack of floating ice often defined as a flat piece at least 20 m across at its widest point, and up to more than 10 km across.[1] Drift ice is a floating field of sea ice composed of several ice floe

First Glaciation Period

This was the Huronian, which was 2.4 to 2.1 billion years ago during the early protozoan Eon.

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. This is 7/8s as dense as water.

Firn line

A line across the glacier, from edge to edge, that marks the transition between exposed glacier ice (below) and the snow-covered surface of a glacier (right). During the summer melt season, this line migrates up-glacier. At the end of the melt season the firn line separates the accumulation zone from the ablation zone.

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 level. The largest Alaskan fiords are more than 100 miles long and more than 5 miles wide. Also spelled Fiord.

Foliation

The layering or banding that develops in a glacier during the process of transformation of snow to glacier ice. Individual layers, called folia, are visible because of differences in crystal or grain size, alternation of clear ice and bubbly ice, or because of entrained sediment.

Fountain

A glacial spring, generally discharging supercooled water with a significant hydrostatic head.

Frazil Ice

Soft or amorphous ice formed by the accumulation of ice crystals in water that is to turbulent to freeze solid. The ice crystals can have diameters of a few millimeters. These crystals are needle like (think satisfying ticktock water).
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G

Glacial flooding

A glacier-dammed outburst flood may be called GLOF or jökulhlaups. Glacial activity is thought to be the cause o Fanny of the largest flooding events in history.

Glacial Formation

A glacier forms when snow accumulates over time, turns to ice, and begins to flow outwards and downwards under the pressure of its own weight.

Glacial Flow

Glaciers flow by basal sliding, internal deformation, and Bed deformation.

Glacial Growth

Glacial growth is most impacted by temperature, precipitation, and sun exposure.

Glacial Groove/Glacial Furrow

A linear depression, inches to miles in length, produced by the removal of rock or sediment by the erosive action of a glacier.

Glacial Lake

An accumulation of standing liquid water on (supraglacial), in (englacial), or under (subglacial) a glacier. Tarns, Finger lakes, and Paternoster lakes are all types of glacial lakes.

Glacial Requirements

Ice must achieve critical mass and be able to flow, AND must be able to last through the summer.

Glacial Stream 

A channelized accumulation of 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. Glaciers are classified by their size, location, and thermal regime.

Glacier Cave 

A cave formed in or under a glacier, typically by running water. Steam or high heat flow can also form glacier caves. Also called Ice Cave.

Glacier Flow 

The movement of ice in a glacier, typically in a downward and outward direction, caused by the force of gravity. 'Normal' flow rates are in feet per day. 'Rapid' flow rates (i.e. surge) are in 10s or 100s of feet per day.

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 not snow crystals! This ice comprises the majority of the mass of a glacier. Intermediate stages include Firn and Neve. This covers~10% of earth. This ice is very very dense, much denser than freezer ice. It is only glacial ice when under 20% air.

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.

Gravimetry

The use of a gravimeter to measure the force of gravity depending on the distance from the earth's core. There is an accelerometer in the gravimeter that does this. Using this, detailed maps can be created judging off the force of gravity. (See Gravimetry map in picture doc)

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H

Hanging Valley

A former tributary glacier valley that is incised into the upper part of a U-shaped glacier valley, higher than the floor of the main valley. Hanging valley streams often enter the main valley as waterfalls.

Holocene

The current part of geologic time. The Holocene epoch began ~12,000 years ago, at the end of the Pleistocene epoch.

Horn

A pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques. Headward erosion has cut prominent faces and ridges into the peak. When a peak has four symmetrical faces, it is called a Matterhorn.
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I

Ice Ages 

An ice age is a long period of time with widespread glaciation. Scientists have recorded five significant ice ages throughout the Earth's history: the Huronian (2.4-2.1 billion years ago), Cryogenian (850-635 million years ago), Andean-Saharan (460-430 mya), Karoo (360-260 mya) and Quaternary (2.6 mya-present).

Ice Rafting

The transportation of glacier sediment away from the ice margin by icebergs. Sediment transported by floating ice and deposited in the ocean is called glacial-marine sediment. Deposited in lakes, it is called glacial-lacustrine sediment.

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. Alaskan icebergs rarely exceed 500 feet in maximum dimension. In order of increasing size, the following names are used: Brash Ice, Growler, Bergy Bit.

Tabular Iceberg

These icebergs have steep sides and a flat top. They have a minimum height to width ratio of 1 to 6. They are some of the largest icebergs in the world.

Non Tabular Iceberg

These are dry dock icebergs, blocky icebergs, and wedge icebergs.

Ice Cores

These are cylinders of ice that are drilled from the ground that show history in layers. These are great to show volcanic eruptions.

Ice-Dammed Lake

A lake that exists because its water is restricted from flowing by an ice dam. Sometimes these lakes form because an advancing glacier had blocked a valley.

Icefall

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-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.

Internal Deformation

Internal deformation occurs predominantly in cold glaciers where gravity and the pressure of ice in the accumulation zone causes ice crystals to slide over each other in a series of parallel planes in a 'crumpling' deformation.

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 caused by advances or retreats of glaciers.
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J-L

Jökulhlaup

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 (Icelandic).

Kame

A sand and gravel deposit formed by running water on stagnant or moving-glacier ice. Crevasse fills or crevasse ridges form within crevasses. Kames form on flat or inclined ice, in holes, or in cracks. A kame terrace forms between the glacier and the adjacent land surface. Shapes include hills, mounds, knobs, hummocks, or ridges.

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 depression enlarges. Kettles often become bogs or peat lands.

Laurentide ice sheet

This was an ice sheet in the most recent ice age, that covers modern day Canada and the northern United States (including northern Indiana). This was the ice sheet that made the Great Lakes.

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.
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M

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. Also called Mass Budget.

Milankovitch

 28 May 1879- 12 December 1958 He was a Serbian mathematician, astronomer, climatologist, geophysicist, civil engineer, and popularizer of science. Primarily known for his Milankovitch Cycles.

Milankovitch Cycles

Small cyclical variations in the shape of Earth's orbit, its wobble and the angle its axis is tilted play key roles in influencing Earth's climate over timespans of tens of thousands to hundreds of thousands of years. This causes Ice-Ages.

The three factors are 

1. The shape of Earth’s orbit, known as eccentricity;

2. The angle Earth’s axis is tilted with respect to Earth’s orbital plane, known as obliquity; and

3. The direction Earth’s axis of rotation is pointed, known as precession.

Moraine

A general term for unstratified and unsorted deposits of sediment that form through the direct action of, or contact with, glacier ice. Many different varieties are recognized on the basis of their position with respect to a glacier. Often described as bands.

·Ablation Moraine 

An irregular-shaped layer or pile of glacier sediment formed by the melting of a block of stagnant ice. Ultimately, ablation moraine is deposited on the former bed of the glacier. Also called Ablation Till.

·Ground Moraine

A blanket of glacier till deposited on all of the surfaces over which a glacier moves, typically by moving ice.

·Ice-cored Moraine

A moraine ridge consisting of a drape of sediment overlying a mass of stagnant ice.

·Lateral Moraine

A sediment ridge, located on a glacier's surface adjacent to the valley walls, extending down glacier to the terminus. It forms by the accumulation of rock material falling onto the glacier from the valley wall, rather than by water deposition. When snow grains grow larger lateral Moraines get smaller.

·Medial Moraine

A sediment ridge, located on a glacier's exposed ice surface, away from its valley walls, extending down glacier to the terminus. It forms by the joining of two lateral moraines when two glaciers merge.

·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.

·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

A cross-valley, ridge-like accumulation of glacial sediment that forms at the farthest point reached by the terminus of an advancing glacier. Also called an End Moraine.

Milankovitch cycles

Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years.

Moulin (Glacier Mill)

A narrow, tubular chute or crevasse through which water enters a glacier from the surface. Occasionally, the lower end of a moulin may be exposed in the face of a glacier or at the edge of a stagnant block of ice.
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N-O

Net Mass Balance

Accumulation-Ablation

Neve

The first year of glacial snow, it is hard and granular, the result of partial melting, re-freezing, and compacting, it forms the surface part of the upper end of a glacier.

Nunatak

A mountain peak or ridge that pokes through the surface of an Ice Field or a Glacier. It may separate adjacent Valley Glaciers (Greenlandic).

Ogive

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- and dark-colored bands. These correspond to a glacier’s seasonal motion.

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 finer grained with increasing distance from the glacier terminus.

Optical Imagery

Satellites collect data through active or passive collection, active; where they emit radiation and measure the wave to make an image. Passive Sattelites measure preexisting waves.
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P

Paleozoic Glaciation

Paleozoic Ice Age (LPIA) and this glaciation is known as the Late Paleozoic Glaciation or Gondwana(n) Glaciation. The LPIA was the longest, most severe, and most widespread icehouse interval of the Phanerozoic. It consisted of multiple, million year-scale glacial episodes that alternated with interglacial/nonglacial conditions of approximately the same duration. Atmospheric CO2 is estimated to have reached the lowest levels and O2 the highest levels of the Phanerozoic. The three supercontinents during this age were the Laurentia, Baltic, and the Gondwana.

Periglaciation 

This is the edges of glacial areas, and this describes the geomorphic processes that result from seasonal thawing and freezing, often in areas with permafrost. Continental it’s affects the extents of periglacion.

Pingos

Pingos are intrapermafrost ice-cored hills, 3–70 m (10–230 ft) high and 30–1,000 m (98–3,281 ft) in diameter.[1] They are typically conical in shape and grow and persist only in permafrost environments, such as the Arctic and subarctic. They are periglacial landforms.

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 covered significant parts of the Earth's surface. Together, the Holocene and Pleistocene epochs comprise the Quaternary Period.

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 glacier ice and transported. This is man made not erosional.

pressure ridge:

a ridge produced on floating ice by buckling or crushing under lateral pressure of wind or tide or on a congealing lava flow by the continued movement of its liquid interior

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Q-R

Radar

Ground penetrating radars send pulses through the ground to measure surfaces and caves and landforms. Kind of like echolocation.

randkluft

: a chasm formed when ice recedes from a mountainside or breaks away from stationary ice

Regelation

Regulation refers to the process where ice melts under pressure and then refreezes when the pressure is reduced. This process typically occurs at the base of a glacier, where the pressure from the overlying ice causes melting. As the ice moves and pressure is relieved, the water refreezes, helping the glacier to flow and move. This process is especially important in the movement of glaciers over uneven terrain.

Remnant

An isolated melting mass of glacier ice, that has become detached from its source and the remainder of the glacier. Some remnants cover many square miles.

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 in a glacier does not move back up the valley.

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.

Rockslide

Several landslides generated by the Great Alaskan Earthquake, Good Friday 1964, fell onto the surface of the so-named glacierin the Chugach Mountains, Alaska.

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 Flour or Glacier Milk.
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S

Sérac

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 séracs.

Seabed Gouging

Seabed gouging by ice is a process that occurs when floating ice features (typically icebergs and sea ice ridges) drift into shallower areas and their keel comes into contact with the seabed. As they keep drifting, they produce long, narrow furrows most often called gouges, or scours. SEE DIAGRAM

Snow: when new layers of snow bury and compress previous layers the snow re-crystallizes into grains the same size and shape as sugar. When snow grains grow larger lateral Moraines get smaller. When snow accumulates it turns into ice.

Snowball Earth events

The two hypothesized snowball earth events were the Sturtian and Marinoan glaciations.

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.

Seismology

The study of movement of materials on earth, such as a volcanic eruption, landslide, or explosion. The waves these movements emit can be used to find the depth of landforms, such as a cave or iceberg.

Striations

Multiple, generally parallel, linear grooves, carved by rocks frozen in the bed of a glacier into the bedrock over which it flows.

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. They may form hexagonal patterns. They are NOT evenly spaced.

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 surge, those that do often surge with some sort of a periodicity.
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T-Z

Tarn

A lake that develops in the basin of a cirque, generally after the melting of the glacier.

Terminus 

The lowermost margin, end, or extremity of a glacier. Also called Toe, End or Snout.

Till (glacial till)

An 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/ accumulation till) or by the melting in-place of stagnant ice (ablation till). After deposition, some tills are reworked by water.

Tillites/Lithified tills

These are sedimentary rocks formed by the lithification of glacial tills.

Till Plain

Till plains are an extensive flat plain of glacial till that forms when a sheet of ice becomes detached from the main body of a glacier and melts in place, depositing the sediments it carries. Till plains have poorly sorted sediment and are formed by the glacier’s direct action, these differentiate till planes from outwash plains.

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 moraine or other sediment deposit; or the boundary between vegetated and bare bedrock.

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.

Varve

A varve is 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 grained winter layer formed from deposition from suspension during a period of winter ice cover. Many varve deposits contain hundreds of couplets.