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Limestone is a common type of carbonate sedimentary rock. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate. Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils, and these provide scientists with information on ancient environments and on the evolution of life.
Clay is a type of fine-grained natural soil material containing clay minerals. Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide.
Rye is a grass grown extensively as a grain, a cover crop and a forage crop. It is a member of the wheat tribe (Triticeae) and is closely related to both wheat (Triticum) and barley. Rye grain is used for flour, bread, beer, crispbread, some whiskeys, some vodkas, and animal fodder. It can also be eaten whole, either as boiled rye berries or by being rolled, similar to rolled oats.
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone through lithification.
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil or as sediment mixed in suspension with water. Silt usually has a floury feel when dry, and lacks plasticity when wet. Silt also can be felt by the tongue as granular when placed on the front teeth.
Soil liquefaction occurs when a cohesionless saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid. In soil mechanics, the term "liquefied" was first used by Allen Hazen in reference to the 1918 failure of the Calaveras Dam in California. He described the mechanism of flow liquefaction of the embankment dam as:
If the pressure of the water in the pores is great enough to carry all the load, it will have the effect of holding the particles apart and of producing a condition that is practically equivalent to that of quicksand... the initial movement of some part of the material might result in accumulating pressure, first on one point, and then on another, successively, as the early points of concentration were liquefied.
Loam is soil composed mostly of sand, silt, and a smaller amount of clay. By weight, its mineral composition is about 40–40–20% concentration of sand–silt–clay, respectively. These proportions can vary to a degree, however, and result in different types of loam soils: sandy loam, silty loam, clay loam, sandy clay loam, silty clay loam, and loam.
Soil mechanics is a branch of soil physics and applied mechanics that describes the behavior of soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids and particles but soil may also contain organic solids and other matter. Along with rock mechanics, soil mechanics provides the theoretical basis for analysis in geotechnical engineering, a subdiscipline of civil engineering, and engineering geology, a subdiscipline of geology. Soil mechanics is used to analyze the deformations of and flow of fluids within natural and man-made structures that are supported on or made of soil, or structures that are buried in soils. Example applications are building and bridge foundations, retaining walls, dams, and buried pipeline systems. Principles of soil mechanics are also used in related disciplines such as geophysical engineering, coastal engineering, agricultural engineering, hydrology and soil physics.
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from shale by its lack of fissility.
The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below :
Petrophysics is the study of physical and chemical rock properties and their interactions with fluids.
Sorghum bicolor, commonly called sorghum and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a grass species cultivated for its grain, which is used for food for humans, animal feed, and ethanol production. Sorghum originated in Africa, and is now cultivated widely in tropical and subtropical regions. Sorghum is the world's fifth-most important cereal crop after rice, wheat, maize, and barley, with 59.34 million metric tons of annual global production in 2018. S. bicolor is typically an annual, but some cultivars are perennial. It grows in clumps that may reach over 4 m high. The grain is small, ranging from 2 to 4 mm in diameter. Sweet sorghums are sorghum cultivars that are primarily grown for forage, syrup production, and ethanol; they are taller than those grown for grain.
In woodworking, a knee is a natural or cut, curved piece of wood. Knees, sometimes called ships knees, are a common form of bracing in boat building and occasionally in timber framing. A knee rafter in carpentry is a bent rafter used to gain head room in an attic.
Sand is a granular material composed of finely divided rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.
Martian soil is the fine regolith found on the surface of Mars. Its properties can differ significantly from those of terrestrial soil, including its toxicity due to the presence of perchlorates. The term Martian soil typically refers to the finer fraction of regolith. So far, no samples have been returned to Earth, the goal of a Mars sample-return mission, but the soil has been studied remotely with the use of Mars rovers and Mars orbiters.
The Lower Greensand Group is a geological unit present across large areas of Southern England. It was deposited during the Aptian and Albian stages of the Early Cretaceous. It predominantly consists of sandstone and unconsolidated sand that were deposited in shallow marine conditions.
Decomposed granite is classification of rock that is derived from granite via its weathering to the point that the parent material readily fractures into smaller pieces of weaker rock. Further weathering yields material that easily crumbles into mixtures of gravel-sized particles known as grus, that further may break down to produce a mixture of clay and silica sand or silt particles. Different specific granite types have differing propensities to weather, and so differing likelihoods of producing decomposed granite. It has practical uses that include its incorporation into paving and driveway materials, residential gardening materials in arid environments, as well as various types of walkways and heavy-use paths in parks. Different colors of decomposed granite are available, deriving from the natural range of granite colors from different quarry sources, and admixture of other natural and synthetic materials can extend the range of decomposed granite properties.
Rocknest is a sand patch on the surface of Aeolis Palus, between Peace Vallis and Aeolis Mons, in Gale crater on the planet Mars. The patch was encountered by the Curiosity rover on the way from Bradbury Landing to Glenelg Intrigue on September 28, 2012. The approximate site coordinates are: 4.59°S 137.44°E.
A number of factors affect the permeability of soils, from particle size, impurities in the water, void ratio, the degree of saturation, and adsorbed water, to entrapped air and organic material.
Barahnaja is an ancient traditional system of multiple cropping that is practised in the Indian mountainous state of Uttarakhand. The term literally means "twelve seeds or food grains" in Garhwali, and refers to the twelve types of crops that are grown together in a single field to enhance soil fertility, food security, and ecological balance. There are no pesticides or fertilizers involved in this method, and many crops in the barahnaja system have medicinal uses. This sustainable and traditional farming method is climate-resilient and has been recognized as "organic by default".
References
- ↑ "Definition of sharp sand". davesgarden.com.
- ↑ livingearth.net Sharp Sand | Living Earth Texas
- ↑ "Definition of SHARP SAND". www.merriam-webster.com.
- ↑ "London Encyclopaedia; Or, Universal Dictionary of Science, Art, Literature and Practical Mechanics: Comprising a Popular View of the Present State of Knowledge". Thomas Tegg. November 16, 1829 – via Google Books.
- ↑ Lyle, Paul (October 27, 2010). Between rocks and hard places: discovering Ireland's northern landscapes. Macmillan. ISBN 9780337095870 – via Google Books.
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