Glacier / Dynamic Planet / Vocabulary

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

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

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; also called a corrie or cwm

cirque glacier

glacier that resides in basins or amphitheaters near ridge crests; most cirque glaciers have a characteristic circular shape

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 hoar

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

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; it is not clear exactly how they are formed and why they form only in some glaciated regions

dump moraine

a mound or layer of moraine formed along the edge of a glacier by rocks that fall off the ice; sometimes called a ground moraine

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; foliation is usually caused by stress and deformation that a glacier experiences as it flows over complex terrain

forbes bands

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

forel stripes

shallow

geyser

fountain that develops when water from a conduit is forced up to the surface of a glacier; also called a negative mill

glacial advance

when a mountain glacier's terminus extends farther downvalley than before; occurs when a glacier flows downvalley faster than the rate of ablation at its terminus

glacial erratic

a boulder swept from its place of origin by glacier advance or retreat and deposited elsewhere as the glacier melted; after glacial melt

glacial grooves

grooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater; also called glacial striations

glacial retreat

when the position of a mountain glacier's terminus is farther upvalley than before; occurs when a glacier ablates more material at its terminus than it transports into that region

glacial striations

grooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater; also called glacial grooves

glacial till

accumulations of unsorted

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

glacier cave

a cave of ice

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; usually flushed out in meltwater streams and causes water to look powdery gray; lakes and oceans that fill with glacier flour may develop a banded appearance; also called rock flour

glacier ice

well-bonded ice crystals compacted from snow with a bulk density greater than 860 kilograms per cubic meter (55 pounds per cubic-foot)

glacier mill

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

glacier pothole

potholes formed at the bottom of glaciers through erosion caused by sand and gravel in melt-water; melt-water seeps through crevasses in the glaciers

glacier remainie

a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier

glacier snout

the lowest end of a glacier; also called glacier terminus or toe

glacier sole

the bottom of the ice of a glacier

glacier table

a rock that resides on a pedestal of ice; formed by differential ablation between the rock-covered ice and surrounding bare ice

glacier terminus

the lowest end of a glacier; also called glacier snout or toe

glacier toe

the lowest end of a glacier; also called glacier snout or terminus

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

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

ice cave

a cave of ice

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

ice stream

a current of ice in an ice sheet or ice cap that flows faster than the surrounding ice

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

jokulhlaup

a large outburst flood that usually occurs when a glacially dammed lake drains catastrophically

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

meltwater conduit

a channel within

moraine

a mound

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; 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