| Marl: Fine textured (silts and clays) highly calcareous unconsolidated material containing shells. This material on the bottom of a lake will give the water an emerald colour. | Mesic: The mid range of the moisture scale from dry to wet; used to refer to vegetation growing in this moisture range. |
Moraine: Rock debris ranging from clay to large block size, that has been transported beneath, beside, on or within and in front of moving ice and deposited on the land surface during both growth and recession of the ice and not modified by any intermediate agent. Lateral moraine – elongate accumulation of rock and soil debris lying on the surface of a glacier in the valley at or near the accumulation of rock and soil debris lying on the surface of a glacier in a valley or near the lateral margin of the glacier. Medial moraine – elongate accumulation of rock and soil debris formed by the joining of adjacent lateral moraines below the juncture of two valley glaciers.
| Nivation hollows: Bowl shaped depressions caused by frost action and mass wasting beneath lingering or perennial snow drifts.
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Oriented Lake: One of a number of lakes having a parallel alignment and commonly elliptical or rectangular in plan. We see this pattern of lakes on the tundra flying from Yellowknife to the Burnside and Coppermine Rivers.
| Palsa: A round or elongated hillock or mound, maximum height of about 10m, composed of a peat layer overlying mineral soil. It has a perennially frozen core which extends from within the covering peat layer downward into or toward the underlying mineral soil.
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Peat: Unconsolidated, compressible material consisting of partially decomposed, semi-carbonized remains of plants such as mosses, sedges and trees, some animal residues, and commonly some mineral soil.
| Peat mound: A mound or hillock in a peatland composed mainly of peat overlying mineral soil.
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Peat Plateau: A low, generally flat-topped expanse of peat, rising one or more metres above the general surface of a peatland. A layer of permafrost exists in the peat plateau, which may extend into the peat below the general peatland surface and even into the underlying mineral soil.
| Peatland: Any terrain covered by a layer of peat.
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Permafrost: The thermal condition of soil or rock of having temperatures below 0C (32F) persist over at least two consecutive winters and the intervening summer. Permafrost occurring everywhere beneath the exposed land surface throughout a geographic regional zone with the exception of widely scattered sites.
| Permafrost, discontinuous: permafrost occurring in some areas beneath the ground surface throughout a geographic regional zone where other areas are free of permafrost.
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Permafrost, widespread: Permafrost that is widely distributed but not continuous beneath the land surface.
| Permafrost table: The upper boundary of permafrost.
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Permafrost thickness: The vertical distance between the permafrost table and the permafrost base.
| Pingo: A conical, commonly more or less asymmetrical mound or hill, with a circular or oval base and commonly fissured summit, which has a core of massive ground ice covered with soil and vegetation, and which exists for at least two winters.
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Pingo, closed system: A generic term for a pingo, in flat, poorly drained terrain of the continuous permafrost zone, that originates where a water-bearing, unfrozen layer of soil, generally in a thaw basin underlying a lake, becomes enclosed by permafrost aggradations (as when a previously existing lake, which provided insulation, shallows or drains completely) causing the expulsion of pore water. The water may dome up the overlying permafrost and inject water that freezes into that layer to form the ice-cored pingo, or the overlying permafrost may be domed up by the segregation of ice.
| Pingo, open system: A generic term for a pingo in areas of marked relief mainly in the discontinuous permafrost zone. An open system pingo originates where the hydrostatic pressure of water circulating from higher ground to beneath a frozen layer causes injection of water which freezes into a weakened part of the overlying layer to form the ice-cored pingo.
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Polygon: A type of patterned ground consisting of a closed, roughly equidimensional figure bounded by several sides, commonly more or less straight but some, or all, of which may be irregularly curved.
| Polygon, high center:
A polygon having a center that is higher than its margins.
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Polygon, low center:
A polygon having a center that is lower than its margins.
| Polygon, nonsorted:
Patterned ground whose mesh is dominantly polygonal and lacks a border of stones.
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Proglacial: Material carried beyond the glacial margins.
| Rock glacier: A glacier-like tongue of angular rock waste usually heading in cirques or other steep walled hollows.
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Scree: A sheet of coarse debris mantling a mountain slope. A frost riven rubble sheet consisting of angular rocks with few lines, resulting from freeze-thaw action and downslope creep.
| Seral: Any stage in the succession of plants from pioneers following disturbances to the climax vegetation.
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Solifluction: The process of slow, gravitational, downslope movement of saturated, unfrozen earth material behaving apparently as a viscous mass over a surface of frozen material. Solifluction features – physiographic features of varying scale produced by the process of solifluction which include: lobe, stripe, sheet, terrace.
| Step: Patterned ground features occurring in groups displaying a step-like form and downslope border of vegetation or stones embanking an area of relatively bare ground up-slope.
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Stone net: A type of patterned ground characterized by a textural differentiation caused by the frost action between fine-grained soils in the center and course grained, stony materials forming the rims of an irregular network of features intermediate between sorted circles and sorted polygons.
| String bog (fen): Boggy area marked by serpentine ridges of peat and vegetation interspersed with depressions many of which contain shallow ponds.
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Stripe, non-sorted: Patterned ground with a striped pattern and a nonsorted appearance owing to parallel lines of vegetation-covered ground and intervening strips of relatively bare ground oriented down the steepest available slope.
| Thermokarst (topography): The irregular topography resulting from the process of differential thaw settlement or caving of the ground because of the melting of ground ice.
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Tor: Isolated masses of rock protruding above the surrounding landscape and consisting of either a single or numerous joint blocks displaying varying degrees of angularity and roundness. Probably more resistant to weathering than the surrounding terrain.
| Tundra: A treeless, generally level to undulating, region of lichens, mosses, sedges, grasses, and some low shrubs, including dwarf willows and birches, which is characteristic of both the Arctic and higher alpine regions outside of the Arctic.
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