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317; Lecture 18
| Term | Definition |
|---|---|
| Periglacial | An environment in the zone peripheral to glaciers OR near-glacial climate conditions |
| Periglaciation | The geomorphic processes that result from repeated cycles of freezing and thawing (physical weathering) |
| Permafrost | Perminantly frozen layer of soil/regolith that is bound together by ice & remains @ or below 0 degrees Celcius for @ least 2 years |
| Active layer | Ground above permafrost which endures seasonal thawing during summer months |
| Talik | A body of unfrozen ground occurring in permafrost |
| Continuous | Permafrost underlying 90% of the landscape |
| Discontinuous | Permafrost with a complex and patchy distribution that is underlying 50-90% of the landscape |
| Sporadic | Permafrost preserved @ scattered sites, northfacing slopes or peat bogs where the peat insulates the permafrost & prevents melting |
| Pore/Interstitial Ice | Ice forms in pore spaces & cements the soil matrix |
| Segregated ground ice | Bodies of pure ice |
| Frost weathering & shattering | A weathering process that creates angular rock debris |
| Frost Heaving & Thrusting | A process where surface stones may be lifted when ice forms |
| Frost cracking | A process where polygonal fracture patterns from expansion & contraction (heating & cooling, wetting & drying) |
| Solifluction | The slow flowage of saturated regolith near the ground surface, either by freeze-thaw or liquefaction |
| Freeze-thaw Cycle | A cycle in which temperatures fluctuate both above and below the freezing point of water |
| Liquefaction | The process by which water-saturated sediment temporarily loses strength & acts as a fluid |
| Nivation | The process of erosion of the ground beneath & @ the sides of a snow bank resulting from freezing & thawing |
| Frost creep | Solifluction that moves material downslope during alternate freeze-thaw cycles |
| Gelifluction | Regolith becomes saturated because water doesn't percolate through frozen permafrost, therefore collecting @ the surface, saturating the soil & creating high hydrostatic pressures which cause liquifaction |
| Ice wedges | V-shaped masses of ground ice that penetrate the active layer & run down into the permafrost |
| Pingo | A perennial frost mound consisting of a core of massive ice covered by soil and vegetation |
| Frost blisters | Seasonal pingos formed in a single winter & melting over a single summer |
| Thermokarst | Irregular terrain characterized by topographic depressions with hummocks (ridges) between them |
| Thaw lakes | A body of water located in thermokarst depressions |
| Solifluction lobes | Tongue-shaped features that form due to differential downhill flow rates |
| Solifluction sheets | Areas of widespread solifluction lobes |
| Rock glaciers | Lobes of frozen angular rock & fine debris mixed with interstitial/pore ice & ice lenses |
| Ice lens | Bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone |
| Cryoplanation terraces | A series of steps & benches that form by scarp retreat as the result of nivation |
| Richter slopes | A landform where debris supply and removal are balanced |
| Permafrost degradation | The deepening of the active layer (more soil ice melts every summer) |
Created by:
turboqueen
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