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Glacier Formation
The process by which snow accumulates, compacts, and transforms into glacial ice over time.
Neve
Granular snow that forms as snow compacts and begins to transform toward glacial ice.
Firn
Densely packed snow that develops from neve under pressure over decades.
Glacial Ice
Ice that forms from the compaction of firn under high pressure and recrystallization.
Crystal Structure of Ice
Ice forms hexagonal crystals which determine its strength and flow characteristics.
Density of Snow
Approximately 50–300 kg/m³.
Density of Firn
Approximately 550 kg/m³.
Density of Glacial Ice
Ranges from approximately 830–917 kg/m³, increasing with compaction.
Accumulation
The addition of snow and ice from processes such as precipitation and avalanches.
Ablation
The loss of ice through processes like melting and sublimation.
Equilibrium Line Altitude (ELA)
The altitude at which accumulation equals ablation in a glacier.
Positive Glacial Budget
Occurs when a glacier advances due to more accumulation than ablation.
Negative Glacial Budget
Occurs when a glacier retreats due to more ablation than accumulation.
Internal Deformation
The process where ice crystals slide past one another under pressure allowing the glacier to flow.
Basal Sliding
The movement of glaciers over a lubricant layer of meltwater at the glacier's base.
Glacial Flow Speed
Faster flow occurs at steeper slopes and higher elevations in glaciers.
Valley/Alpine Glaciers
Glaciers located in mountainous regions.
Cirque Glaciers
Glaciers that occupy bowl-shaped depressions.
Hanging Glaciers
Glaciers that end at steep cliffs.
Piedmont Glaciers
Glaciers that spread out at the base of mountains.
Ice Sheets
Massive glaciers covering large areas, such as those in Antarctica and Greenland.
Ice Streams
Fast-moving channels within ice sheets.
Ice Shelves
Floating extensions of glaciers that protrude from land.
Ice Caps
Smaller, dome-shaped glaciers covering less area than ice sheets.
Ice Tongues
Glaciers that extend into the ocean.
Crevices
Deep cracks in the surface of glaciers created by stress.
Ogives
Alternating bands of light and dark ice linked to seasonal flow.
Ice Falls
Steep descents of glaciers that resemble frozen waterfalls.
Calving
The process where icebergs break off from ice shelves into the ocean.
Marine Ice Sheet Instability
A phenomenon where ocean warming causes destabilization of ice sheets.
Ice Shelf Buttressing
The stabilization of inland glaciers provided by the presence of ice shelves.
Cirques
Bowl-shaped hollows carved by glacier erosion.
U-Shaped Valleys
Valleys formed by the erosive action of glaciers on valley walls.
Hanging Valleys
Tributary valleys left above the main U-shaped valley after glacial erosion.
Aretes
Sharp ridges formed between adjacent glacial valleys.
Horns
Pointed peaks shaped by glacial erosion on all sides.
Striations
Grooves in bedrock formed by rocks embedded in moving ice.
Roche Moutonnée
Smooth, asymmetrical bedrock features formed by glaciers.
Moraines
Accumulations of debris deposited by glaciers, categorized by position relative to the glacier.
Terminal Moraines
Deposits formed at the furthest extent of a glacier.
Ground Moraines
Deposits left underneath a glacier.
Kames
Mounds of sediment deposited by meltwater.
Drumlins
Streamlined hills of till formed by glacier movement.
Eskers
Long, winding ridges of sediment deposited by subglacial rivers.
Erratics
Large boulders transported and deposited by glaciers.
Tarns
Small lakes formed in cirques.
Kettles
Depressions formed by melting ice blocks that leave behind low-lying areas.
Moraine-Dammed Lakes
Lakes that form behind moraines blocking drainage.
Permafrost
Permanently frozen ground that remains at a temperature below 0°C for at least two consecutive years.
Pingos
Ice-cored hills resulting from groundwater freezing.
Frazil Ice
Needle-like crystals forming in calm water.
Pancake Ice
Circular slabs that form in turbulent water.
Draft vs. Freeboard
Comparison between submerged and above-water portions of ice.
Pressure Ridges
Ridges formed by the collision and deformation of ice.
Surface Melt
Seasonal melting that contributes to the formation of supraglacial lakes.
Moulins
Vertical shafts that transport meltwater to the base of glaciers.
Subglacial Lakes
Lakes located beneath glaciers, important for understanding glacial hydrology.
Greenhouse Gases
Gases like CO₂ and CH₄ that are released from melting ice, contributing to climate change.
Albedo Effect
The warming effect caused by the loss of reflective ice surfaces.
Isostatic Rebound
The rise of land that occurs after glaciers have melted away.
Milankovitch Cycles
Orbital changes that regulate solar energy distribution, influencing glacial cycles.
Varves
Annual layers of sediment deposited in glacial lakes, representing seasonal deposition.
Outwash
Sorted sediments that result from glacial meltwater activity.
Till
Unsorted debris deposited directly by glaciers.
Altimetry
A method to measure changes in ice surface height.
Radar
Technique used to reveal ice thickness and subglacial features.
Seismology
The study of icequakes and subglacial processes using seismic methods.
Gravimetry
Method of mapping gravitational variations to estimate ice mass.
Ice Cores
Cylinders of ice drilled from glaciers that contain gases and aerosols indicating past climates.
Glacial Hazards
Risks associated with glaciers, like ice avalanches and GLOFs (Glacial Lake Outburst Floods).
