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soil glossary
| Term | Definition |
|---|---|
| Alluvial fan | A fan shaped deposit of alluvium, laid down by a stream where it emerges from an upland to less steeply sloping terrian |
| Alluvium | Material such as clay, slit, sand and gravel deposited by modern rivers and streams |
| Bed | A unit layer, 1 cm or more thick, that is visually or physically more or less distinctly separable from other layers above and below in a stratified sequence |
| Bedrock | The solid rock that underlies the soil and the regolith, or that is exposed at the surface |
| Calcareous soil | Soil containing sufficient calcium carbonate, often with magnesium carbonate, to effervesce visibly with cold 0.1N (10%) hydrochloric acid |
| Capillary fringe | A zone of essentially saturated soil just above the water table. The size distribution of the pores determines its extent |
| Clay | As a particle size term: a size fraction less than 0.002mm in equivalent diameter |
| Clayey | Containing large amounts of clay, or having properties similar to those of clay |
| Colloid | A substance in a state of fine subdivision, whose particles are 10-4 to 10-7 in diameter |
| Consistence | The resistance of a material to deformation or rupture |
| Consolidation | The gradual reduction in volume of soil mass resulting from an increase in compressive stress |
| Creep | Slow mass movement of soil and soil material down rather steep slopes primarily under the influence of gravity, but aided by saturation with water and by alternate freezing and thawing. In engineering: general slow displacement |
| Crushing strength | The force required to crush a mass of dry soil, or conversely the resistance of a mass of dry soil to crushing |
| Delocculate | To separate the individual components of compound particles by chemical or physical means or both. to cause the particles of the dispersed phase of a colloidal system to become suspended in the dispersion medium |
| Delta | A fan shaped area at the mouth of a river formed by the deposition of large layers of sediment brought down from the land and spread out on the bottom of a basin. where the current reaches quiet water, the bulk of the coarser load is dropped and the finer |
| Deposit | Material left in a new posistion by a natural transporting agent such as water, wind, ice or gravity or by the activity of man |
| Drumlin | An elongate or oval hill of glacial drift, commonly glacial till, deposited by glacier ice and having its long axis parallel to the direction of ice movement |
| Dunes | Wind-built ridges and hills of sand formed in the same manner as snowdrifts. They are started by some obstruction, such as a bush, boulder or fence that causes an eddy or otherwise thwarts the sand laden wind. |
| Eolian deposit | Sand or silt or both deposited by the wind |
| Erosion | wearing of the land by running water, ice, wind, and other geological agents such as gravitational creep. detachment and movement of soil or rock by water, wind, ice or gravity |
| Erratic | a transported rock fragment different from bedrock where it lies. the term is generally applied to fragments transported by glacier ice or by floating ice |
| Esker | a winding ridge of irregularly stratified sand, gravel and cobbles deposited under the ice by a rapidly flowing glacial stream |
| Fines | a term used in soil mechanics for the portion of soil finer than a number 200 U.S. standard sieve |
| Firm | a term describing the consistence of moist soil that offers distinctly noticeable resistance to crushing, but can be crushed with moderate pressure between the thumb and forefingerq |
| Flood plain | the land bordering a stream, built up of sediments from overflow of the stream and subject to inundation when the stream is at flood stage |
| Fluvial deposits | all sediments, past and present, deposited by flowing water, including glaciofluvial deposits. wave worked deposits and deposits resulting from sheet erosion and mass wasting are not included |
| Friable | a consistence term pertaining to the ease of crumbling soils |
| Frost action | freezing and thawing of moisture in materials and the resultant effects on these materials and on the structures of which they are a part or with which they are in contact |
| frost heave | the raising of a surface caused by ice in the underlying soil |
| glacial drift | all rock materials carried by glacier ice and glacier meltwater or rafted by icebergs. this term includes till, stratified drift and scattered rock fragments |
| glacial till | unstratified glacial drift deposited directly by ice and consisting of clay, sand and gravel and boulders intermingled in any proportion |
| glaciofluvial deposits | material moved by glaciers and subsequently sorted and deposited by streams flowing from the melted ice. the deposits are stratified and may occur in the form of outwash plains, deltas, kames, eskers and kames terraces |
| ground moraine | unsorted mixture of rocks, boulders, sand, silt, and clay deposited by glacial ice. predominant material is till, but some stratified drift is present. most of till is thought to have accumulated under the ice by lodgement; |
| horizon | layer soil or soil material approximately parallel to the land surface. it differs from adjacent genetically related layers in properties such as colour, structure, texture, consistence and chemical, biological, and mineralogical composition |
| hydraulic conductivity | the proportionnality factor in Dacry's law applied to the viscous flow of water in soil, that is, the flux of water per unit gradient of the hydraulic potential |
| hydraulic head | the elevation with respect to a specified reference level at which water stands in a piezometer connected to the point in question in the soil |
| hydrologic cycle | the conditions through which water naturally passes from the time of precipitation until it is returned to thee atmosphere by evaporation and is ready again to be precipitated |
| infiltration rate | a soil characteristic determining or describing the maximum rate at which water can enter the soil under specified conditions, including the pressure of excess water |
| inorganic soil | a soil made up mainly of mineral particles (greater 17% carbon) |
| ion | atom, group of atoms, or compound that is electrically charged as a result of the loss of electrons (cation) or the gain of electrons (anions) |
| kame | an irregular ridge or hill of stratified glacial drift deposited by glacial meltwater |
| kettle | depression left after the melting of a detached mass of glacier ice buried by drift |
| lacustrine deposit | material deposited in lake water and later exposed either by lowering of the water level or by uplifting of the land. these sediments range in texture from sands to clays |
| landforms | the various shapes of the land surface resulting from a variety of actions such as deposition or sedimentation (eskers, lacustrine basins) erosion (gullies, canyons) and earth crust movements (mountains) |
| liquefaction | the sudden, large decrease of the shearing resistance of a cohesion-less soil. it is caused by a collapse of the structure by shock or other strain and is associated with a sudden, temporary transformation of the material into a fluid mass |
| liquid limit | the water content corresponding to an arbitrary limit between the liquid and plastic states of consistence of a soil. the water content at which a pat of soil, cut by a standard-size groove, will flow together for a distance of 12mmundertheimpactof25blows |
| loess | material transported and deposited by wind and consisting of predominantly silt-sized particles |
| marl | a soft, unconsolidated earthly deposit consisting of calcium carbonate or magnesium carbonate, or both and often shells, usually mixed with varying amounts of clay or other impurities |
| mass wasting | a general term for a variety of processes by which large masses of earth material are moved by gravity from one place to another |
| metamorphic rock | rock derived from preexisting rocks, differing from them in physical, chemical and mineralogical properties as a result of natural geological processes, principally heat and pressure, originating within the earth. may have been igneous, sedimentary rock |
| mineral | a homogeneous naturally occurring phase, sometimes restricted to inorganic, crystalline phases |
| montmorillonite | a specific aluminous member of the smectite group i.e. an expanding clay |
| moraine | an accumulation of earth, generally with stones, carried and finally deposited by glacier |
| parent rock | the rock from which the parent materials of soil are formed |
| particle size analysis | the determination of the various amounts of the different separates in a soil sample, usually by sedimentation, sieving or micrometry or a combination of these methods |
| particle size distribution | the amount of various soil separates, in a soil sample, |
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