Dynamic Planet Vocab V1

Ablation Area

The area of a glacier where more glacier mass is lost than gained.

Ablation Hollows

Depressions in the snow surface caused by the sun or warm, gusty wind.

Ablation Moraine

Mound or layer of moraine in the ablation zone of a glacier; the rock has been plucked from the mountainside by the moving glacier and is melting out on the ice surface.

Ablation Season

Period during which glaciers lose more mass than they gain; usually coincides with summer.

Ablation Zone

Area or zone of a glacier where snow and ice ablation exceed accumulation.

Accumulation Area

Area of a glacier where more mass is gained than lost.

Accumulation Season

Period during which a glacier gains more mass than it loses usually coincides with winter.

Accumulation Zone

Area of a glacier where more mass is gained than lost.

Advance

When a mountain glacier's terminus extends farther down valley than before; glacial advance occurs when a glacier flows down valley faster than the rate of ablation at its terminus.

Alpine Glacier

A glacier that is confined by surrounding mountain terrain; also called a mountain glacier.

Arête

Sharp, narrow ridge formed as a result of glacial erosion from both sides.

Band Ogives

Alternate bands of light and dark on a glacier; usually found below steep narrow icefalls and thought to be the result of different flow and ablation rates between summer and winter.

Basal Sliding

The sliding of a glacier over bedrock.

Bergschrund

Crevasse that separates flowing ice from stagnant ice at the head of a glacier.

Branched-Valley Glacier

Glacier that has one or more tributary glaciers that flow into it; distinguished from a simple valley glacier that has only a single tributary glacier.

Catchment Glacier

A semi permanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a snowdrift glacier or a drift glacier.

Chattermarks

Striations or marks left on the surface of exposed bedrock caused by the advance and retreat of glacier ice.

Cirque

Bowl shaped or amphitheater usually sculpted out of the mountain terrain by a cirque glacier.

Cirque Glacier

Glacier that resides in basins or amphitheaters near ridge crests; most cirque glaciers have a characteristic circular shape, with their width as wide or wider than their length.

Cold Glacier

Glacier in which most of the ice is below the pressure melting point; nonetheless the glacier's surface may be susceptible to melt due to incoming solar radiation.

Compression Flow

Flow that occurs when glacier motion is decelerating down-slope.

Constructive Metamorphism

Snow metamorphism that adds molecules to sharpen the corners and edges of an ice crystal.

Crevasse

Open fissure in the glacier surface.

Crevasse ****

A kind of hoarfrost; ice crystals that develop by sublimation in glacial crevasses and in other cavities with cooled space.

Dead Ice

Any part of a glacier which has ceased to flow; dead ice is usually covered with moraine.

Dirt Cone

A cone-shaped formation of ice that is covered by dirt; a dirt cone is caused by a differential pattern of ablation between the dirt-covered surface and bare ice.

Drain Channel

Preferred path for meltwater to flow from the surface through a snow cover.

Drift Glacier

A semi-permanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a catchment glacier or a snowdrift glacier.

Drumlin

Remnant elongated hills formed by historical glacial action.

Dump Moraine

A mound or layer of moraine formed along the edge of a glacier by rocks that fall off the ice.

End Moraine

An arch-shaped ridge of moraine found near the end of a glacier.

Equilibrium Zone

Zone of a glacier in which the amount of precipitation that falls is equal to the amount that melts the following summer.

Esker

A sinuous ridge of sedimentary material (typically gravel or sand) deposited by streams that cut channels under or through the glacier ice.

Extending flow

When glacier motion is accelerating down-slope.

False ogives

Bands of light and dark on a glacier that were formed by rock avalanching.

Fjord

Glacial troughs that fill with seawater.

Foliation

Layering in glacier ice that has distinctive crystal sizes and/or bubbles.

Forbes bands

Alternate bands of light and dark on a glacier; usually found below steep narrow icefalls.

Forel stripes

Shallow, parallel grooves on the face of a large melting ice crystal.

Geyser

Fountain that develops when water from a conduit is forced up to the surface of a glacier.

Glacial advance

When a mountain glacier's terminus extends farther downvalley than before.

Glacial Erratic

A boulder swept from its place of origin by glacier advance or retreat and deposited elsewhere as the glacier melted.

Glacial grooves

Grooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater.

Glacial retreat

When the position of a mountain glacier's terminus is farther upvalley than before.

Glacial striations

Grooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater.

Glacial till

Accumulations of unsorted, unstratified mixtures of clay, silt, sand, gravel, and boulders.

Glacial trough

A large u-shaped valley formed from a v-shaped valley by glacial erosion.

Glaciated

Land covered in the past by any form of glacier is said to be glaciated.

Glacier

A mass of ice that originates on land, usually having an area larger than one-tenth of a square kilometer.

Glacier cave

A cave of ice, usually underneath a glacier and formed by meltwater.

Glacier fire

A phenomenon in which strong reflection of the sun on an icy surface causes a glacier to look like it is on fire.

Glacier flood

A sudden outburst of water released by a glacier.

Glacier flour

A fine powder of silt- and clay-sized particles that a glacier creates as its rock-laden ice scrapes over bedrock.

Glacier ice

Well-bonded ice crystals compacted from snow with a bulk density greater than 860 kilograms per cubic meter.

Glacier mill

A nearly vertical channel in ice that is formed by flowing water.

Glacier pothole

Potholes formed at the bottom of glaciers through erosion caused by sand and gravel in melt-water.

Glacier remainie

A glacier that is reconstructed or reconstituted out of other glacier material.

Glacier snout

The lowest end of a glacier.

Glacier sole

The bottom of the ice of a glacier.

Glacier table

A rock that resides on a pedestal of ice.

Glacier terminus

The lowest end of a glacier.

Glacier toe

The lowest end of a glacier.

Glacier trough

U-shaped valleys transformed from v-shaped stream valleys due to erosion caused by passing glaciers.

Glacieret

A very small glacier.

Glacierized

land overlaid at present by a glacier is said to be covered; the alternative term glacierized has not found general favour.

Ground moraine

continuous layer of till near the edge or underneath a steadily retreating glacier.

Hanging glacier

a glacier that terminates at or near the top of a cliff.

Hanging valley

a valley formed by a small glacier that has a valley bottom relatively higher than nearby valleys formed by larger glaciers.

Headwall

a steep cliff, usually the uppermost part of a cirque.

Horn

a peak or pinnacle thinned and eroded by three or more glacial cirques.

Ice apron

a mass of ice adhering to a mountainside.

Ice cap

a dome-shaped mass of glacier ice that spreads out in all directions; an ice cap is usually larger than an icefield but less than 50,000 square kilometers (12 million acres).

Ice cave

a cave of ice, usually underneath a glacier and formed by meltwater; cave entrances are often enlarged near a glacier terminus by warm winds; most common on stagnant portions of glaciers.

Ice covered

land overlaid at present by a glacier is said to be covered; the alternative term glacierized has not found general favor.

Ice divide

the boundary separating opposing flow directions of ice on a glacier or ice sheet.

Ice quake

a shaking of ice caused by crevasse formation or jerky motion.

Ice sheet

a dome-shaped mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres) (e.g., the Greenland and Antarctic ice sheets).

Ice stream

(1) a current of ice in an ice sheet or ice cap that flows faster than the surrounding ice (2) sometimes refers to the confluent sections of a branched-valley glacier (3) obsolete synonym of valley glaciers.

Ice-cemented glacier

a rock glacier that has interstitial ice a meter or so below the surface.

Ice-cored glacier

a rock glacier that has a buried core of ice.

Icefall

part of a glacier with rapid flow and a chaotic crevassed surface; occurs where the glacier bed steepens or narrows.

Ice field

a mass of glacier ice; similar to an ice cap, and usually smaller and lacking a dome-like shape; somewhat controlled by terrain.

Jokulhlaup

(1) a large outburst flood that usually occurs when a glacially dammed lake drains catastrophically (2) any catastrophic release of water from a glacier.

Lateral moraine

a ridge-shaped moraine deposited at the side of a glacier and composed of material eroded from the valley walls by the moving glacier.

Marginal crevasse

a crevasse near the side of a glacier formed as the glacier moves past stationary valley walls; usually oriented about 45 degrees up-glacier from the side wall.

Medial moraine

a ridge-shaped moraine in the middle of a glacier originating from a rock outcrop, nunatak, or the converging lateral moraines of two or more ice streams.

Meltwater conduit

a channel within, underneath, on top of, or near the side of a glacier that drains meltwater out of the glacier; usually kept open by the frictional heating of flowing water that melts the ice walls of the conduit.

Moraine

a mound, ridge, or other distinct accumulation of glacial till.

Moraine shoal

glacial moraine that has formed a shallow place in water.

Moulin

a nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses; also called a pothole.

Mountain glacier

a glacier that is confined by surrounding mountain terrain; also called an alpine glacier.

Negative mill

a geyser; a fountain that develops when water from a conduit is forced up to the surface of a glacier.

Niche glacier

very small glacier that occupies gullies and hollows on north-facing slopes (northern hemisphere); may develop into cirque glacier if conditions are favorable.

Nunatak

a rocky crag or small mountain projecting from and surrounded by a glacier or ice sheet.

Ogives

alternate bands of light and dark ice seen on a glacier surface.

Outburst flood

any catastrophic flooding from a glacier; may originate from trapped water in cavities inside a glacier or at the margins of glaciers or from lakes that are dammed by flowing glaciers.

Outlet glacier

a valley glacier which drains an inland ice sheet or ice cap and flows through a gap in peripheral mountains.

Paternoster lakes

a series of tarns connected by a single stream or a braided stream system.

Piedmont glacier

large ice lobe spread out over surrounding terrain, associated with the terminus of a large mountain valley glacier.

Polar glacier

a glacier entirely below freezing, except possibly for a thin layer of melt near the surface during summer or near the bed; polar glaciers are found only in polar regions of the globe or at high altitudes.