Soil Flashcards
The top layer of earth’s surface, consisting of disintegrated rock and decayed organic matter suitable for the growth of plant life.
Soil
The fertile surface layer of soil, as distinct from the subsoil.
Topsoil
The bed or layer of earth immediately beneath the surface soil.
Subsoil
Perennially frozen subsoil in arctic or subarctic regions.
Permafrost, pergelisol
The unbroken, solid rock that underlies all unconsolidated material on the earth’s surface, such as soil, clay, sand or rock fragments.
Bedrock
Soil containing a large amount of organic matter, usually very compressible and having poor load-sustaining properties.
Organic Soil
A diagram of a vertical section of soil from the ground surface to the underlying material, showing a succession of horizons developed by weathering, deposition, or both.
Soil Profile
Any of a series of relatively distinct layers of soil or its underlying material found in a vertical section of land.
Horizon
A single bed or layer of sedimentary earth or rock having the same composition throughout, lying between beds of another kind.
Stratum
A process for determining the particle-size distribution in an aggregate, soil or sediment.
Soil Analysis
A numerical classification of soil by texture, used by the US Department of Agriculture. 1 - Gravel
2 - Sand
3 - Clay
4 - Loam
5 - Loam with some sand
6 - silt-loam
7 - Clay-loam
Soil Class
A large, naturally rounded rock, lying on the surface of the ground or partially embedded in it.
Boulded
A naturally rounded stone, smaller than a boulder and larger than a pebble, used for rough paving, walls, and foundations.
Cobble, Cobblestone
Small pebbles and stones, or a mixture of these with sand, formed either naturally or by crushing rock, esp such material that will pass a 3in sieve and be ratained on a no.4 (4.8mm) sieve.
Gravel
Gravel having one or more fractured faces produced by mechanical crushing.
Crushed Gravel
Stone having well-defined edges produced by the mechanical crushing of rocks or boulders.
Crushed Stone, Crushed Rock
A small-diameter, natural gravel, usually 1/4” to 3/8” (6.4 to 9.5mm) in size, screened to specification.
Pea Gravel
A small, rounded stone, especially one worn smooth by the action of water.
Pebble
A loose, granular material resulting from the disintegration of rocks, consisting of grains smaller than gravel but coarser than silt.
Sand
A well-graded, naturally occurring sand often used as a base or subbase material, having about 10% clay or just enough to make the mixture bind tightly when compacted.
Sand Clay
Loose sedimentary material consisting of fine mineral particles between 0.002mm and 0.05mm in diameter.
Silt
A natural, earthy material that is plastic when moist but hard when fired and is used for making brick, tile, and pottery, composed mainly of fine particles of hydrous aluminum silicates less than 0.002mm in diameter.
Clay
A clay formed by the decomposition of volcanic ash, having the ability to absorb large amounts of water and expand to several times its natural volume.
Bentonite
A rich soil containing a relatively equal mixture of sand and silt and a smaller proportion of clay and organic matter.
Loam
An unstratified, cohesive, loamy deposit deposited by wind,
Loess
The levels of water content defining the boundaries between the different states of consistency of a plastic or cohesive soil, as determined by standard tests.
Atterberg Limits
The water content, expressed as a percentage of dry weight, at which a soil passes from a plastic to a liquid state.
Liquid Limit
The numerical difference between the liquid limit and the plastic limit of a soil.
Plasticity index
The water content, expressed as a percentage of dry weight, at which a soil loses its plasticity and begins to behave as a solid.
Plastic Limit
A soil that can be rolled into threads 1/8” in diameter without crumbling.
Plastic Soil
The water content, expressed as a percentage of dry weight, at which a reduction in water content will not cause a further decrease in the volume of a soil mass.
Shrinkage Limit
Soil that has considerable strength when unconfined and air-dried, and significant cohesion when submerged.
Cohesive Soil
Soil that has little or no strength when unconfined and air-dried, and little or no cohesion when submerged.
Cohesionless Soil
The consolidation of sediment by the weight of overlying deposits, or a similar compression of soil, aggregate, or cementitious material by rolling, tamping, or soaking.
Compaction
The water content of a soil at which maximum density can be attained through compaction.
optimum moisture content
Any gravel, sand or silt that exhibits no cohesiveness or plasticity.
Granular Material
The property of a porous material that allows a gas or liquid to pass through its pore spaces.
Permeability
The ratio of the volume of void spaces to the volume of solid particles in a soil mass.
Void Ratio
The void ratio corresponding to the critical density of a soil mass.
Critical Void Ratio
The unit weight of a saturated granular material above which it will gain strength and below which it will lose strength when subjected to rapid deformation.
Critical Density
A test for measuring the density of granular soils and the consistency of some clays at the bottom of a borehole, recording the number of blows required by a hammer to advance a standard soil sampler.
Penetration Test
The unit load required to produce a specified penetration into a soil at a specified rate of penetration.
Penetration Resistance
Any permeable soil that allows the relatively free movement of water.
Pervious Soil
Any fine-grained soil, such as clay, having pores too small to permit water to pass except by slow capillary action.
IMpervious Soil
The property of a soil that enables its particles to resist displacement with respect to one another when an external force is applied, due largely to the combined effects of cohesion and internal friction.
Shearing Strength, Shearing Resistance
