GLACIOSPELEOLOGY AND GLACIAL GLOSSARY

                                                 By Charles H. Anderson Jr. Director

 International Glaciospeleological Survey

ABLATION.  Refers to all processes by which snow, ice owater in any form are lost from a glacier.

ABLATION AREA. Is the lower region of a glacier where snow ablation exceeds snowfall.

ACCUMULATION AREA. Is the upper region of a glacier when snow accumulation exceeds melting.

ALBEDO. Is the percentage of the imcoming radiation that is reflected off a surface. An albedo of one indicates that 100 percent of the radiation is reffected.

BACON ICE DRAPEREY. Is a form of ice in the shape of a bacon.

BASALT. Is a common type of lava. Aa and pahoehoe are foms of basalts.

BREAKDOWN. s any ice or other material which has fallen form the ceiling o wall of a cave, but usally applied to considerable accumulations.                                                        

CAVE ICE. Is ice naturally formed in a cave.

CAVE MILE. Is 5,280 feet underground passage in glacier, snow, firn or rock.

COLUMN. A compound speleothem produced by fusion of a stalactite and stalagmite. Cf. piller.

CREVASSES. Are open fissures in a glacier.

CIRQUE. Is a deep, steep-walled recess in a mountain, caused by glacial erosion.

DENSITY. Is the ratio of the mass of an object to its volume. Snow has a density averaging about 0.1 and the glacier ice has a density of about 0.89. The density of unmineralized fresh water is 1.            

ESKERS. They are long narrow ridges. They may be deposits from streams of melted ice that run through tunnels in a glacier.

EQUILIBRIUM LINE. Is the boundary between the accumulation area and the ablation area.

FLAKE. Is a slab of ice which peels away from the wall or ceiling of a glacier or firn cave.

FIRN. Is old snown that has been recrystalized into a more dense substance. Firn has a density grater than 0.55.

FIRN CAVE. A cave in snow which has not compacted sufficently to develop the density of a glacier.

FORMATION. Is a geological term referring to a specific unit of bedrock. A confusing popular term for speleothem. Or anything which has form in a cave a very loose and confusing usage.

FUMAROLE. Is a outlet for volcanic gasses. A few are cavernous.

GLACIERE. Same as ice cave, but also including cold-trapping sites of other kinds.

GEOTHERMAL. Pertaining to the internal heat of the earth.

GEOTHERMAL CAVE. Is a cave produced by geothermal melting of snow or ice.

GLACIAL ADAVANCE. Is the net movement of glacier teminus downvalley. Advance occurs when the rate of glacier flow downvalley is grater than its rate of ablation. Advances are characterized by convex-shaped terminus.

GLACIAL DRIFT. Is the loose and unsorted rock debris distributed by glaciers and glacial meltwaters.

GLACIAL FLOUR. Is the fine-grained sediment carried by glacial rivers that results from the abrasion of rock at glacier bed. Its presence turns lake waters agua blue or brown, depending on its parent rock type.

GLACIAL POLISH. Is the leveling and smoothing of rock by fine-grained debris at glacier the bed.

GLACIAL RETREAT. Is the net movement of the glacier terminus upvalley. Retreat results when the glacier is ablating at a rate faster than its movement downvalley. Rrtreating termini are usually concave in shape.  Glacier. Is a body of ice showing evidence of movement as reported by the presence of ice flowlines, crevasses, and recent geologic evidence.

GLACIER CAVE. Is a cave in or beneath a glacier.

GLACIERE. Is is a ice cave, but also including cold trapping sits of othe kinds.

GLACIOHYDROLOGY. The study of underground water and its actions in glaciers.

GLACIORIBBON. An unbanded drapery which other wouldbe termed bacon ring in ice.

GLACIOSPELEOGENESIS. The process of and development of glacier caves.

GLACIOSPELEOTHEM. A ice deposit form in a glacier, fin, snow and caves.

GLACIOSPELEOLOGICAL. Is the study of glacier caves and related other phenomena.

GLACIOSPELEOLOGIST. Is a scientist that studies glacier, firn and snow caves and other phenormena.

GROTTO. Is a smallside chamber of a cave.

HELICTITE. Is a speleothem which looks as if it ought to have become a stalactile but seemingly ignoredthe law of gravity. While most are contorted or forked and some are straight.

HELIGMITE. A helictite directed upward, "like a stalagmite".

HYDROLOGY. Speleologically, the study of under ground water and its action.

HYDROTHERMAL ALTERATION. Is the alteration of rocks or minerals due to the reactions of geothermally heated water with minerals. The process weathers and weakens the rocks such that they may become unstable.

ICEFALLS. Icefalls are somewhat analogous to waterfalls in rivers. The flow of the ice down a steep gradient often results in crevasses and seracs.

INTERNATIONAL GLACIOSPELEOLOGICAL SURVEY OR IGS.  Is a group of glaciospeleologits that studies and maps glacier, firn and snow caves and other related phenomena in glacies aound the world.

JOKULHLAUPS. They are sudden outburts of water released by a glacier. The water may be released from a glcaier cave or cavitiest, sub-glacier lakes, and from glacier dammed lakes.

KETTLES. When the last ice sheets melted. Large isolated blocks of ice remained burried in glacial tills. When these blocks melted, depressions, called Kettles.

KINEMATIC WAVES. Is refer to a wave of ice moving downglacier propagated by its increased thickness. The wave of ice may move at two to six times the velocity of surrounding thinner ice.

LAHAR. Is a mudflow or debris flow originating on a volcano.

LATERAL MORAINES. Ae piles of loose unsorted rocks along the sides magins of the glacier. The rocks may be pushed there by the moving ice or dumped from the glacier's rounded surface. Describes the net gain or loss of snow and ice through a given year. It is usually expessed in terms of wate gain or loss.

MEDIAL MORAINES. They are form where two mountain glacies bearing lateral moraines unite. They appear as dark streak of rock along the glacier centerline.

MORAINE. A landform composed of till or drift.

MOULIN. Is a domepit-like stucture of glaciers. In winter a moulin will become a pillar or column as water will freeze in winter which flows through the moulin.

NEOGLACIATION. Is refers to the advances made by mounyain glaciers since the great Pleistocence ice age. In the Cascades the advances have occurred since 6,600 years before present.

OGIVES. They are arc-shaped features occasacionally found across the glacier suface below icefalls. They may be ridges and swales in the ice or bands of darker or lighter ice. One theory of their formation suggests that the ice is stretched and sometimes dritied when exposed in the icefall during the high velocities of summer; it is compressed duing the winter so that bands of different ice thickness forms.

OUTBURST FLOODS. Jokuhlhaups; sudden reseases of water stored in or adjacent to a glacier, glacier cave or in a glacier lake.

OUTWASH. A stratified deposits produce by glacial meltwater.

PERMAFROST. Permanent ice within alpine or arctic portions of the earth's crust.

PERFECTLY PLASTIC SOLID. They are a solid that does not deform untill it reaches a critical value of stress, after which it will yield infinitely.

PILLAR. A solitary vertical or nearly vertical glacier ice or bedrock remnant.

PLASTIC FLOW. A change in shape of a solid that takes place without rupture.

PLEISTOCENE. This is a period of earth's histoy, roughly two million years ago to about ten thousand years ago, characterized by the advance and recession of the continental ice sheets.

PROGLACIAL. Is immediately in front of or just beyound the limits of a glacier.

PSEUDOKARST. A karst-like phenomena og glacies, lava flows and other poorly soluble rocks, resulting from processes other than solution.

ROCHE MOUTONNEE. Is a small asymetrically-shape hill form by glacial erosin. The upper sides are rounded and smoothed and the lower sides are rough and broken due to quarrying by the glacier.

SERARS. Are the pinnacles of ice formed where the glacier surface is torn by sets of crevasses.

ROCKFALL. The process of breakdown.

ROCK FLOWER. Fine rock particles produced by glacial pulverization.

SCALLOP. An unevenly rounded, shallow pocket on the suface of glacier ice, bedrock, mud and other substances, occurring in groups.

SINK. A depression in cavernous cavernous country resulting from a collapse of underlying cavern.

SINKHOLE. Essentially identical with sink.

STRIATION. A scratch or groove on rock produced by passage of a glacier.

SKYLIGHT. A comparatively small gap in the roof of a cave or glacier and allowing entry of only a little daylight.

SNOW CAVE. A natural cave in snow formed by the same processes which creat glacier caves.

SODA-STRAW STALACTITE. A thin walled, hollow, tubula stalactite approximately the diameter of a drop of water.

SPELEOTHEM. A mineral depost formed in a cave.

SQUEEZEWAY. A cavern passage so narrow that human passage is difficult.

STEAM CAVE. See geothermal cave.

STALACTITE. Remember the popular minemonic: they Cling to the ceiling.

STALAGMITE. Ergo, they gow from the ground.

STRIATIONS. Are the scratches etched into the rock at the bed of the glacier. Their presence indicates ging of sand and rock particles into the bed under considerable pressure.

SUNCUB. Is a small depression on a snow or firn surface formed by melting and evaporation esulting from direct exposure to the sun.

TERMINUS. Is the downvalley end of a glacier. It is sometimes referred to as the glacier snout.

TERMINAL MORAINES. Are piles of loose unconsoildate rock at the glacier's down-valley end. The rocks may be pushed there by the forward motion of the glacier or dumped from the glacier's rounded surface.

TILL. Is the unsorted rock debris deposited directly by the glacier without the extreme reworking by meltwater.

TRIMLINES. Are the sharp vegetative boundaries delimiting the upper margin of a former glaciation. The age differences of the ground surface are often visible because of different ages of the vegetation.

VALLEY GLACIE. A glacier that heads at a cirque or cirques and then flows into, and is confined by, a valley; an alpine glacier.

WINDOW, KARST OR PSEUDOKARSTIC. A type of collapse sink which has unroofed a sufficient length of cavern or underground stream to allow entry of essentially full daylight.