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Cryosphere – portion of hydrosphere and groundwater that is perennially frozen
Glacial formation – occurs at north/south poles, high elevations (mountain ranges)
Glacier – large persistent body of ice that rests on land or floats on sea, and in which accumulation
exceeds ablation (melting/subliming)
Mass balance/budget – difference between accumulation and ablation
Two main techniques for studying mass balance:
Probing – placing poles at various points in ice during beginning of ablation/accumulation period and later
studying change in the height of the ice along the poles
Crevasse stratigraphy – observing number of layers formed in crevasses to determine how much snow
Névé – accumulation of snow that has been partially melted, refrozen, and compacted
Firn – intermediate recrystallized state between snow and ice; névé that survives a full season of
ablation; weight of snow on top compresses snow on bottom, turning it into ice (blue from lack of
Two forms of glacial movement – spreading and basal slip (pressure causes ice on bottom to melt,
reduces friction and allows slide)
Less pressure on upper layers > more brittle – fracture and form crevasses
Glaciohydraulic supercooling – process that allows water at base of glacier to remain in liquid state
below freezing temperature
Accumulation area/zone – cold temperatures, snow collects and adds mass; larger in winter
Ablation area/zone – warm temperatures, glacier melts; larger in spring/summer
Snow/firn line – separates zones of accumulation and ablation
Icebergs – chunks of ice that fall off glacier/ice shelf into ocean from calving; tabular – flat-topped
Moulins/potholes – vertical tubes that carry meltwater down through the glacier
Seracs – jagged columns/blocks of ice; intersection of multiple crevasses or when softer ice falls off
denser ice; can easily collapse; found within icefall
Icefall – place where glacier moves over cliff; part of glacier with rapid flow and chaotic crevassed
Ogives – alternating dark/light bands of ice occurring on glacier surfaces, only below icefalls
Two types – alpine/valley glaciers (high elevations, basal slip) and ice sheets/continental glaciers
(continental masses of glacial ice, ex. Antarctica, Greenland, Arctic Ocean)
Ice shelves – occur when ice sheets extend over the sea and float on water
Ice caps –dome-shaped ice shelves that cover area of less than 50,000 km2 and completely bury
underlying landscape
Ice streams – channelized glaciers that flow more rapidly than surrounding ice
Icefields – extend in elongated patterns over mountainous regions
Piedmont glaciers – occur when steep valley glaciers spill out into relatively flat plains; spread out into
bulb-like lobes
Hanging glacier/ice apron – wide glacier that clings to walls of glacial valleys; often causes avalanches
Glacial valleys:
U-shaped valley/glacial trough – originally V-shaped river valley that was eroded by alpine glacier that
moved through and removed rock from the sides through plucking and abrasion
Tunnel valley – large, long U-shaped valley originally cut under glacial ice near ice sheet margins;
formed by subglacial erosion through water; served as drainage pathways carrying meltwater;
appear as dry valleys, lakes, seabed depressions, and sediment-filled areas; most run from north
to south
Urstromtal/meltwater valley/ice-marginal valley – broad glacial valley formed during Ice Ages by
meltwaters parallel to ice region; appear in front of glacier, unlike tunnel valleys, which appear
Tidewater glaciers – valley glaciers that flow far enough to reach the sea; high acceleration rates; calve
Outlet glaciers – channels of ice that flow out of ice sheet, constrained by bedrock on sides
Valley glaciers – provide drainage for icefields; surrounded by exposed bedrock and slopes, which
provide snow and ice to accumulate via avalanches; fjords are formed after valley glaciers retreat
and water fills the depression
Catchment/snowdrift/drift glaciers – semi-permanent masses of firn formed by drifted snow behind
obstructions or in the ground
Isostatic depression – glacier forces liquid in mantle out of the way
Isostatic rebound – slow process in which mantle refills space and pushes crust back up into original
position after glacier recedes
Fjord – long, narrow inlet with steep sides; formed when glacier cuts U-shaped valley by ice segregation
and abrasion of surrounding bedrock
Misfit stream – stream/river that is too large/small to have eroded the valley in which it flows
Overfit stream – too large; underfit stream – too small
Hanging valley – tributary valley with floor at higher elevation than main channel into which it flows;
often has waterfall through outlet
Glaciers act like conveyor belts, picking up rocks along the way and later depositing them
Sometimes rocks are crushed by glacier weight into rock flour (which sometimes appears in thick,
grayish meltwater)
Glacial erratics – large rocks transported by glaciers into prominent locations
Striations – scrapes in bedrock caused by rocks being transported by glaciers
Chatter marks – intermittent scrapes
Till – unsorted, coarsely graded sediment (part of glacial drift deposited directly by glacier)
Moraines – glacially formed accumulation of unconsolidated debris (soil and rock); depositional
Lateral moraines – parallel ridges deposited along sides and on top of glacier
Ground/dump moraines – till-covered areas with irregular, rolling (usually gentle) topography
and no ridges; often found between two lateral moraines in alpine glaciers; deposited
between glacial ice and underlying bedrock, behind end moraines; may change into
drumlins by overriding ice
Rogen/ribbed moraines – form series of ribs in ice sheet; sometimes filled with water
End/terminal moraines – deposited at end of glacier, marking maximum advance; reflect shape
of glacier’s terminus/snout; size and shape determined by whether glacier is advancing,
retreating, or at equilibrium; more accumulation the longer the terminus stays in one place
Recessional moraines – series of ridges running across valley behind terminal moraines; reside
between and are perpendicular to lateral moraines
Medial moraines – ridges that run down center of valley floor; formed when two glaciers meet;
debris join and are then deposited
Supraglacial moraines – accumulated on top of glacial ice
Washboard moraines – shaped like washboards
Veiki moraines – hummocky (cross-bedded) moraines that form irregular landscapes of ponds
and plateaus surrounded by banks
Outwash – sediments deposited by glacial meltwater
Outwash plain/Sandur – plain formed of glacial sediments deposited by meltwater outwash at
terminus of glacier
Outwash fan – fan-shaped body deposited by braided streams
Esker – long, winding ridge of outwash (stratified sand and gravel) deposited in streams that flow through
base of glacier
Kame – irregularly-shaped hill or mound composed of till that accumulates in depression on retreating
glacier; associated with kettles; depositional
Roche moutonnée/Sheepback – asymmetrical rock formations and hills; indicates glacier flow from one
side, which is smooth, to the other side, which is jagged; results from abrasion on “stoss” (up-ice)
side of rock and plucking on “lee” (down-ice) side
Drumlins – elongated, oval-shaped hills; narrower side indicates direction of glacier flow; depositional
Pyramidal peak – mountaintop created by erosion of multiple glaciers on central point; extreme form
called glacial horn
Aréte – narrow ridge of rock usually formed when two glaciers erode parallel U-shaped valleys
Col/Saddle/Spillway – lowest point of aréte between two peaks/cirques
Cirque/corrie/cwm – bowl-shaped depression created when glaciers erode backwards into
mountainsides; cirque glaciers may be created in these
Tarn/Corrie loch – mountain lake or pool formed in a cirque
Ribbon lakes – long and narrow lakes usually found in glacial troughs
Kettle lakes – form, often from melting cirque glaciers, when pieces of ice break off and become buried
by till; small and pond-like; depositional
Paternoster lakes – series of glacial streams connected by single stream or braided stream system, like
a rosary; occur in alpine valleys; created by end moraines
Jökulhlaup – sudden flood that occurs when glacial lake is released
Theories of glacial advance and retreat (glacial periods):
Milankovitch Cycles (eccentricity – deviation of orbit shape from perfect circle, obliquity – tilt of
axis, precession – wobble of axis); shifting of tectonic plates; particles expelled by
volcanoes or meteoric impacts; atmospheric composition; solar variability; insulation; dust;
atmospheric composition; ocean current circulation; sea ice; and atmospheric circulation
Periglacial – relating to conditions, processes, and landforms associated with cold, non-glacial
environments; includes geomorphic processes related to freezing of water
Permafrost – condition where layer of soil, sediment, or rock below ground surface remains frozen for
more than a year
Continuous permafrost – exists over landscape as uninterrupted layer
Discontinuous permafrost – has numerous, scattered, small thawed areas
Sporadic permafrost – consists of small islands scattered in unfrozen areas
Alpine permafrost – found in higher elevations
Subsea permafrost – exists below seawater
Active layer – upper zone of soil that experiences daily and seasonal freeze-thaw cycles
Taliks – unfrozen layers located on top, underneath, or within masses of permafrost
Frost heaving – upward and outward movement of ground surface resulting from formation of ice
beneath surface of soil; ice grows in direction of heat
Frost-susceptibility – determined by size of voids in soil (grain-size distribution)
Periglacial processes:
Weathering – operates in repeated cycles of freeze-thaw; responsible for rock fracturing
Ground/anchor ice – bodies of ice in ground surface of permafrost layer
Pore ice – found in spaces that exist between particles of non-frost-susceptible soil/sediment
Needle ice – groups of small, narrow ice slivers; formed in moist soil; loosens soil for erosion and
moves small rocks up to soil surface; enhances soil creep
Ice wedges – downward, narrowing bodies of ice that form from seasonal cracks in the ground
and grow; cycles of ice addition can be identified as foliations, or layers; called sand
wedges when accumulation of wind-blown sand occurs
Segregated ice – masses of almost pure ice that grow in frost-susceptible soil as a result of liquid
water diffusion from unfrozen parts of soil
Ice lenses – layer of horizontal accumulation, usually of segregated ice
Mass movement – downslope movement of sediment, soil, and rock material
Solifluction – characterized by freeze-thaw action, water-logged soil, slow movement, and
formation of U-shaped features (solifluction lobes)
Gelifluction – form of solifluction in which material slides over slick permafrost layer
Frost creep – initiated by frost heaving and thawing with small amounts of stress
Rockfall – detachment and movement of rock from cliff face to its base; fracturing of rock along
natural bedding planes and joints due to frost wedging and insolation weathering (physical
weathering due to thermal expansion and contraction)
Erosion – removal of weathered sediment and rocks by wind, water, and ice
Nivation – associated with isolated patches of snow that remain through summer season; involves
processes of frost weathering at margins of snow patches, meltwater erosion, and
gelifluction; often creates nivation hollows under snow patches
(A)eolian erosion/deposition – processes in which strong winds move large quantities of loose
sediment and soil, especially during summer months
Fluvial erosion/deposition – processes in which discharge (rate of flow) of streams fluctuate;
when suddenly reduced, large quantities of gravel and boulders are left behind; beaded
channels develop when streams pass over ice wedges and melt them to form deep pools
Entrainment – picking up of loose material by glacier from along bed and valley sides
Periglacial landforms:
Patterned ground – presence of ground materials arranged in a variety of symmetrical, geometric
shapes; associated with frost sorting
Palsas – low, often oval-shaped permafrost mounds with layers of segregated ice and peat (partially
decomposed remains of plants); contain permanent ice lenses; develop in bogs from groundwater;
found in areas with discontinuous permafrost; arise in groups
Pingo/hydrolaccolith – ice-cored hill, usually circular in shape, which can only form in permafrost
environment by hydrostatic pressure or groundwater flowing from outside source; larger than
palsas; smaller pingos have rounded tops while larger ones have exposed ice that may melt into
Thermokarst – irregular surfaces of marshy hollows and hummocks (rounded knolls of ice) formed as
ice-rich permafrost thaws; ice melting beneath thermokarst lakes cause them to deepen over time
Thufur – huge hummocks that form in seasonally frozen ground or in permafrost areas
Blockfield/Everest/Felsenmeer – area covered by large, frost-shattered angular blocks of stone;
created by freeze-thaw action
Rock glacier – thick lobe- or tongue-shaped mass of ice and talus (coarse rock fragments) that has
moved slowly downslope through deformation of internal ice; formed by either glacial or periglacial
processes; deposition of debris from cirque headwall is regulated by rate of headwall erosion and
point of origin of debris along headwall (sometimes catastrophic rockfalls take place), which control
movement of individual lobes and overall formation as well as affect morphology
Active rock glacier – moves downslope or downvalley; contains substantial amounts of deforming
ice; steep frontal slope; contrast with inactive rock glacier
Fossil rock glacier – does not contain ice; surface is frequently covered by vegetation; gradient
of front slope is less steep than that of active rock glaciers
Negative mill – geyser that develops when water from conduit is forced up to surface of glacier
Nunatak – rocky outcrop projecting from and surrounded by glacier or ice sheet
Bergschrund – crevasse that separates flowing ice from stagnant ice at head of glacier
Randkluft – fissure that separates moving glacier from headwall rock
Regelation – motion of object through ice by melting and freezing due to pressure differences
Sintering – bonding together of ice crystals
Thomson crystal – large ice crystal found in deep, stagnant water-filled cavities
Ice tongue – projection of ice edge (up to several kilometers in length) out from coastline; caused by
wind and currents and usually forms when valley glacier moves rapidly into lake or ocean
Constructive metamorphism – process in which snow changes shape and adds molecules to sharpen
corners and edges of ice crystal
Diagenesis – chemical, physical, or biological change undergone by sediment after initial deposition and
during and after lithification (becoming solid rock), not counting weathering and metamorphism
Groove – elongated depression carved out of bedrock by rock particles contained in base of glacier
Pleistocene – geological epoch from 2,588,000 to 11,700 years ago; recent period of recent glaciations;
1st of Quaternary Period, 6th of Cenozoic Era; at maximum, 30% of Earth was covered by ice; large
lakes accumulated because outlets were blocked and cooler air slowed evaporation; 11 major
glacial events termed glacials/pluvials, which were separated by interglacials/interpluvials;
minor advances and retreats called stadials
Pre-Pleistocene glacial record:
Archaean (pre-2500 Ma (megaanum, or millions of years)); Early Proterozoic (2500 → 1650 50 Ma) –
extensive continental glaciation and glacio-marine deposition at intervals of 3-4 Ma; Late Proterozoic
(1650 50 → 590 Ma) – no glacial activity until about 1000 Ma ago; Cambrian (590 → 505 Ma) – welldocumented tillites few in number; Ordovician (505 → 440 Ma) – next major glacial event occurred late
in this era; Silurian (440 → 412 Ma) – glacial activity waned everywhere except in South America, where
it waned in Late Silurian Period; Devonian (412 → 365 Ma); Carboniferous (365 → 290 Ma) – best
known of pre-Pleistocene glaciations; Permian (290 → 235 Ma) – more extensive distribution in Australia
and less in South America; Triassic (235 → 192 Ma); Jurassic (192 → 135 Ma) – possible sea ice
Oxygen isotope ratio cycle – describes period changes in ratio of
isotopes and water
temperature, which are directly linked;
is the most common, followed by