Glossary Terms, Winter Term 2013

Term Definition
Acid soil A soil material having a pH of less than 7.0, usually understood to be less than 6.0
Adsorbed water Water held in a soil mass by physiochemical forces having pysical properties substantially different from absorbed water or chemically combined water at the same temperature and pressure
air-dry The state of dryness of a soil at equilibrium with the moisture sat_flash_1 of the surrounding atmosphere; the moisture sat_flash_1 depends on the relative humidity and temperature of the surrounding atmosphere
Alkali soil A soil having a high degree of alkalinity (pH 8.5 or higher) or having an exchangeable sodium sat_flash_1 (15% or more of the exchange capacity) or both
Bearing capacity the average load per unity area that is required to rupture a supoorting soil mass
Breccia A rock composed of coarse angular gragments cemented in a fine grained matrix
Bulk density The mass of dry soil per unit bulk volume. The bulk volume is determined before the soil is dried to constant weight at 105 degrees C. It has been called apparent density
Clay As a particle size term: a size fraction less than 0.002mm in equivalent diameter
Compressibility The susceptibility of a soil to decrease in volume when subjected to load
Conservation Protection of the soil against physical loss by erosion or against chemical deterioration; that is excessive loss of fertility by either natural or artifical means
Consistence The resistance of a material to deformation or rupture
Creep Slow mass movement of soil and soil material down rather steep slopes primarily under the influence of gravity but aide by saturation with water and by alternate freezing and thawing. In engineering – general slow displacement under load.
Cross-bedding An arrangement in which thin layers of stratified sediment are transverse or oblique to the main plane of stratification
Crushing strength The force required to crush a mass of dry soil, or conversely the resistance of a mass of dry soil to crushing. It is expressed in units of force per unity area (pressure)
Crystal A homogeneous inorganic substance of definite chemical composition bounded by plane surfaces that form definite angles with each other to give the substance a regular geometric form
Drain To provide channel such as open ditched or drain tile so that excess water can be removed by surfaces that form definite angles with each other to give the substance a regular geometric form
Erode To wear away or remove the land surface by qind, water or other agents
Fine tecture Consisting of or containing large quantities of the fine fractions (silt and clay)
Glacial till Unstratified glacial drift deposited directly by ice and consistin of clay sand and gravel and boulders intermingled in any proportion
Gleysation A soil forming process, operating under poor drainage conditions which reults in the reductions of iron and other elements in gray colours, and mottles
Humus The fraction of the soil organic matter that remains after most of the added plant and animal residues have decomposed. It is usually dark coloured. It is also used in a collective term for the surgace organic matter deposits: mor, moder, mull, muck
Hydrogenic soil Soil developed under the influence of water standing within the profile for prolonged periods; it is formed mainly in cold, humid regions
Hydrolysis The process by which a substrate is split to form two end products by the intervention of a molecule of water
Hygroscopic water Water absorbed by a dry soil from an atmosphere of high relative humidits water lost from an air dyr soil when it is headted to 105 degress
Illite A hydrous mica
Infiltration The downward entry of water into the soil
Mass wasting A general term for a variet of processes by which large masses of earth material are moved by gravity from one place to another
Mica A mineral group consisiting of phyllosilicates, having sheetlike 2:1 lattive structures, generally with potassium in the interlayer position
Mine dump Area covered with overburden and other waste material from ore and coal mines, quarries and smelters, and usually having little or no vegetative cover
Mine wash Water deposited accumulations of sandy, silty, or clayey material recently eroded in mining operations. It may clog streams and channels and damage land on which it is deposited
Montmorillonite group Clay minerals having 2:1 expanding crystal lattive. Isomorphous substitution gives the various types and causes a net permanent charge balanced by cations in such a manner that water may not move…
Mottled zone Layer that is marked with spots or blotches of a redder hue or deeper shades of a hue (chroma). The pattern of mottling and size, abundance, and colour contrast of the mottles vary markedly anf should be specified in the soil description
Mottles Spots or blotches of different colour or shades of colour interspersed witht he dominant colour
Outwash Sediments washed out of the flowing water beyond the glacier and laid down as stratified drift. The particle size may vary from boulders to silt
Pans Horizons or layers in soils that are strongly compacted, or very high in clay sat_flash_1
Parent material The unconsolidated and more or less chemically weathered mineral or organic matter from which the solum of a soil has developed by pedogenic processes
Particle density The mass per unit volume of the soil particles. It is usually expressed in grams per cubic centimeter
Penetrability The ease at which a probe can be pushed into the soil that are caused by a physical foreces, and are descrive by or expressed in, physical tersm or equations
Piezometer An instrument for measuring the pressure head of liquids
Plastic soil A soil capable of being molded or deformed continously and permanently into various shapes by moderate pressure
Pore space The toal space not occupied by soil particles in bulk volume of the soil
Relief Elevations or inequalities of a land surface, considered collectively. Land having no enevennes or differences of eleveation is called level
Residual material Unconsolidated and partly weather minerals formed by the disintegration of consolidated rock in place
Residual soil Soil formed from, or resting on, consolidated rock of the same kind as that from whcih it was formed and in the same location
Reworked Descriptive of material modified after its preliminary deposition, commonly by water or wind
Runoff The poriton of the total preciptation of an area that flows away through stream channels
Soil formation factors The variable, usually interrelated natural agencies that are responsible for the formation of soil. The factors are: parent rock, climate, organisms, relief and time
Solum The upper horizons of a soil in which the parents material has been modified and in which most plant roots are contained. It usually consists of A and B horizons
Stabilization Chemical or mechanical treatment designed to increase or maintain the stability of a mass of soil or otherwise to improve its engineering properties
Stratified drift Materials that are distinctly sorted according to size and weight of their component fragments, indicating a medium of transport (water or wind) more fluid than glacier ice
Stress Adirectional force acting within a material
Substrate That which is spread under i.e an underlying layer, such as the subsoil
Talus A sloping heap of loose rock fragments lying at the foot of a clipp of a steep slope
Varve A distinct band representing the annual deposit of sedimentary materials, regardless or origin. It usually consists of two layers, a thick light coloured layer of silt and fine sand laid down in the spring and summer, and a thin, dark coloured layer of
Void Space in a soil mass not occupied by solid mineral matter. This space may be occupied by air, water or orther gaseous or liquid material
Bulk volume The volume, including the solids and the pores, of a soil mass
Dry weight percentage The ratio of the weight of any constituent of a soil in the oven dry weight of the soil
Igneous rock Rock formed by the cooling and solidification of magma. It has not changed appreciably since its formation
Indicator plants Plants that are characteristic of a specific soil or site condition
Landscape All natural features such as fields, hills, forests, and water that distinguish one part of the earth's surface from another part.
Landslide A mass of material that has slipped downhill by gravity often assisted by water, when the material is saturated. A rapid movement of a mass of soil, rock, or debris, down a slope
Soil moisture Water contained in the soil
Moisture-weight percentage The moisture sat_flash_1 expressed as a percentage of the oven dry wieght of the soil
Organic matter The organic fraction of the soil; includes plant and animal reidues at a various stages of decomposition, cells and tissues of soil organisms…
Ovendry soil Soil that has been dried at 105 degrees C until it has reached a constant weight
Peat Unconsolidated soil material consistin largely of undecomposed, or only slightly decomposed, organic matter
Physical properties of soil The charcteristics, processes or reactions of a soil that are caused by physical forces, and are describes by or expressed in, physical terms or equations
Piezomenteric surface The surface at which water will stand in a series of piezometers
Quicksand Sand of low bearing capacity cause by the upward flow of the water and the resultant decrease in intergranular pressure
Sandy Containining a large amount of sand. It may be applied to any one of the soil classes that contains a large percentage of sand.
Seepage The escape of water downard through the soil. The emergence of water from the soil along an extensive line of surface in contrast to a spring where the water emerges from a local spot
Stoke's law An equation relating to the terminal settling velocity of a smooth, rigid sphere in a viscous fluid of known densitt and viscosity to the diameter of the sphere when subjected to a known force
Void ratio The ratio of the volume of void space to the volume of solid particles in a given soil mass
Soil water Is understood to be the equilibrium solution in the soil

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