Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is similar to the formation of dew, except it occurs below the freezing point of water typically without crossing through a liquid state.
A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.
Weathering is the deterioration of rocks, soils and minerals through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs in situ, and so is distinct from erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically have a concave upwards form, where the maximum inclination corresponds to the angle of repose of the mean debris particle size. The exact definition of scree in the primary literature is somewhat relaxed, and it often overlaps with both talus and colluvium.
A cirque is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie and cwm. A cirque may also be a similarly shaped landform arising from fluvial erosion.
Frost heaving is an upwards swelling of soil during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where freezing temperatures have penetrated into the soil. Ice growth requires a water supply that delivers water to the freezing front via capillary action in certain soils. The weight of overlying soil restrains vertical growth of the ice and can promote the formation of lens-shaped areas of ice within the soil. Yet the force of one or more growing ice lenses is sufficient to lift a layer of soil, as much as 1 foot or more. The soil through which water passes to feed the formation of ice lenses must be sufficiently porous to allow capillary action, yet not so porous as to break capillary continuity. Such soil is referred to as "frost susceptible". The growth of ice lenses continually consumes the rising water at the freezing front. Differential frost heaving can crack road surfaces—contributing to springtime pothole formation—and damage building foundations. Frost heaves may occur in mechanically refrigerated cold-storage buildings and ice rinks.
Plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the weathering and erosion of pieces of bedrock, especially large "joint blocks". This occurs in a type of glacier called a "valley glacier". As a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock. The freezing and thawing action of the ice enlarges, widens, or causes further cracks in the bedrock as it changes volume across the ice/water phase transition, gradually loosening the rock between the joints. This produces large chunks of rock called joint blocks. Eventually these joint blocks come loose and become trapped in the glacier.
Premelting refers to a quasi-liquid film that can occur on the surface of a solid even below melting point. The thickness of the film is temperature dependent. This effect is common for all crystalline materials. Premelting shows its effects in frost heave, and, taking grain boundary interfaces into account, maybe even in the movement of glaciers.
A joint is a break (fracture) of natural origin in a layer or body of rock that lacks visible or measurable movement parallel to the surface (plane) of the fracture. Although joints can occur singly, they most frequently appear as joint sets and systems. A joint set is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A joint system consists of two or more intersecting joint sets.
In fluid statics, capillary pressure is the pressure between two immiscible fluids in a thin tube, resulting from the interactions of forces between the fluids and solid walls of the tube. Capillary pressure can serve as both an opposing or driving force for fluid transport and is a significant property for research and industrial purposes. It is also observed in natural phenomena.
Needle ice is a needle-shaped column of ice formed by groundwater. Needle ice forms when the temperature of the soil is above 0 °C (32 °F) and the surface temperature of the air is below 0 °C (32 °F). Liquid water underground rises to the surface by capillary action, and then freezes and contributes to a growing needle-like ice column. The process usually occurs at night when the air temperature reaches its minimum.
Palsas are peat mounds with a permanently frozen peat and mineral soil core. They are a typical phenomenon in the polar and subpolar zone of discontinuous permafrost. One of their characteristics is having steep slopes that rise above the mire surface. This leads to the accumulation of large amounts of snow around them. The summits of the palsas are free of snow even in winter, because the wind carries the snow and deposits on the slopes and elsewhere on the flat mire surface. Palsas can be up to 150 m (490 ft) in diameter and can reach a height of 12 m (39 ft).
Ice jacking occurs when water permeates a confined space within a structural support or a geological formation, ultimately causing structural fracture when the water freezes and expands. The force from this expansion can damage shorelines, rock faces, and other natural environments. This has the potential to lead to property damage and environmental changes. Ice jacking most commonly refers to shoreline damage caused by lakes freezing, but it has also been applied to geologic engineering and rock erosion. When this occurs within rocks, it is called ice wedging. When this occurs within the soil, it is called frost heaving or ice heaving. It is similar in appearance to, but not to be confused with, ice shove, which is a pile-up of ice on a shoreline.
A frost boil, also known as mud boils, a stony earth circles, frost scars, or mud circles, are small circular mounds of fresh soil material formed by frost action and cryoturbation. They are found typically found in periglacial or alpine environments where permafrost is present, and may damage roads and other man-made structures. They are typically 1 to 3 metres in diameter.
Frost crack or Southwest canker is a form of tree bark damage sometimes found on thin barked trees, visible as vertical fractures on the southerly facing surfaces of tree trunks. Frost crack is distinct from sun scald and sun crack and physically differs from normal rough-bark characteristics as seen in mature oaks, pines, poplars and other tree species.
Ice lenses are bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing crack, and, as long as the conditions remain favorable, continues to collect in the ice layer or ice lens, wedging the soil or rock apart. Ice lenses grow parallel to the surface and several centimeters to several decimeters deep in the soil or rock. Studies from 1990 have demonstrated that rock fracture by ice segregation is a more effective weathering process than the freeze-thaw process which older texts proposed.
Frost weathering is a collective term for several mechanical weathering processes induced by stresses created by the freezing of water into ice. The term serves as an umbrella term for a variety of processes, such as frost shattering, frost wedging, and cryofracturing. The process may act on a wide range of spatial and temporal scales, from minutes to years and from dislodging mineral grains to fracturing boulders. It is most pronounced in high-altitude and high-latitude areas and is especially associated with alpine, periglacial, subpolar maritime, and polar climates, but may occur anywhere at sub-freezing temperatures if water is present.
Cryosuction is the concept of negative pressure in freezing liquids so that more liquid is sucked into the freezing zone. In soil, the transformation of liquid water to ice in the soil pores causes water to migrate through soil pores to the freezing zone through capillary action.
Overdeepening is a characteristic of basins and valleys eroded by glaciers. An overdeepened valley profile is often eroded to depths which are hundreds of metres below the lowest continuous surface line along a valley or watercourse. This phenomenon is observed under modern day glaciers, in salt-water fjords and fresh-water lakes remaining after glaciers melt, as well as in tunnel valleys which are partially or totally filled with sediment. When the channel produced by a glacier is filled with debris, the subsurface geomorphic structure is found to be erosionally cut into bedrock and subsequently filled by sediments. These overdeepened cuts into bedrock structures can reach a depth of several hundred metres below the valley floor.
