Gravel /ˈɡrævəl/ is a loose aggregation of rock fragments. Gravel is classified by particle size range and includes size classes from granule- to boulder-sized fragments. In the Udden-Wentworth scale gravel is categorized into granular gravel (2 to 4 mm or 0.079 to 0.157 in) and pebble gravel (4 to 64 mm or 0.2 to 2.5 in). ISO 14688 grades gravels as fine, medium, and coarse with ranges 2 mm to 6.3 mm to 20 mm to 63 mm. One cubic metre of gravel typically weighs about 1,800 kg (or a cubic yard weighs about 3,000 pounds).
Gravel is an important commercial product, with a number of applications. Many roadways are surfaced with gravel, especially in rural areas where there is little traffic. Globally, far more roads are surfaced with gravel than with concrete or tarmac; Russia alone has over 400,000 km (250,000 mi) of gravel roads. Both sand and small gravel are also important for the manufacture of concrete.
Large gravel deposits are a common geological feature, being formed as a result of the weathering and erosion of rocks. The action of rivers and waves tends to pile up gravel in large accumulations. This can sometimes result in gravel becoming compacted and lithified into the sedimentary rock called conglomerate. Where natural gravel deposits are insufficient for human purposes, gravel is often produced by quarrying and crushing hard-wearing rocks, such as sandstone, limestone, or basalt. Quarries where gravel is extracted are known as gravel pits. Southern England possesses particularly large concentrations of them due to the widespread deposition of gravel in the region during the Ice Ages.
The word gravel comes from the Breton language. In Breton, "grav" means coast. Adding the "-el" suffix in Breton denotes the component parts of something larger. Thus "gravel" means the small stones which make up such a beach on the coast. Many dictionaries ignore the Breton language, citing Old French gravele or gravelle.
Gravel often has the meaning a mixture of different size pieces of stone mixed with sand and possibly some clay. In American English, rocks broken into small pieces by a crusher are known as crushed stone.
Types of gravel include:
In locales where gravelly soil is predominant, plant life is generally more sparse. This outcome derives from the inferior ability of gravels to retain moisture, as well as the corresponding paucity of mineral nutrients, since finer soils that contain such minerals are present in smaller amounts.
Media related to Gravel at Wikimedia CommonsAlluvium
Alluvium (from the Latin alluvius, from alluere, "to wash against") is loose, unconsolidated (not cemented together into a solid rock) soil or sediment that has been eroded, reshaped by water in some form, and redeposited in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel. When this loose alluvial material is deposited or cemented into a lithological unit, or lithified, it is called an alluvial deposit.Aurboða
In Norse mythology, Aurboða (also Aurboda) (Old Norse "gravel-bidder" or "gravel-offerer") is a mountain jötunn, wife to the jötunn Gymir, and mother of Gerðr.Breccia
Breccia ( or ) is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix that can be similar to or different from the composition of the fragments.
The word has its origins in the Italian language, in which it means either "loose gravel" or "stone made by cemented gravel". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia, and hydrothermal breccia.Conglomerate (geology)
Conglomerate () is a coarse-grained clastic sedimentary rock that is composed of a substantial fraction of rounded to subangular gravel-size clasts, e.g., granules, pebbles, cobbles, and boulders, larger than 2 mm (0.079 in) in diameter. Conglomerates form by the consolidation and lithification of gravel. Conglomerates typically contain finer grained sediment, e.g., either sand, silt, clay or combination of them, called matrix by geologists, filling their interstices and are often cemented by calcium carbonate, iron oxide, silica, or hardened clay.
The size and composition of the gravel-size fraction of a conglomerate may or may not vary in composition, sorting, and size. In some conglomerates, the gravel-size class consist almost entirely of what were clay clasts at the time of deposition. Conglomerates can be found in sedimentary rock sequences of all ages but probably make up less than 1 percent by weight of all sedimentary rocks. In terms of origin and depositional mechanisms, they are closely related to sandstones and exhibit many of the same types of sedimentary structures, e.g., tabular and trough cross-bedding and graded bedding.Construction aggregate
Construction aggregate, or simply "aggregate", is a broad category of coarse to medium grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under foundations, roads, and railroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete.
Preferred bituminous aggregate sizes for road construction are given in EN 13043 as d/D (where the range shows the smallest and largest square mesh grating that the particles can pass). The same classification sizing is used for larger armour stone sizes in EN 13383, EN 12620 for concrete aggregate, EN 13242 for base layers of road construction and EN 13450 for railway ballast.
The American Society for Testing and Materials publishes an exhaustive listing of specifications including ASTM D 692 and ASTM D 1073 for various construction aggregate products, which, by their individual design, are suitable for specific construction purposes. These products include specific types of coarse and fine aggregate designed for such uses as additives to asphalt and concrete mixes, as well as other construction uses. State transportation departments further refine aggregate material specifications in order to tailor aggregate use to the needs and available supply in their particular locations.
Sources for these basic materials can be grouped into three main areas: Mining of mineral aggregate deposits, including sand, gravel, and stone; use of waste slag from the manufacture of iron and steel; and recycling of concrete, which is itself chiefly manufactured from mineral aggregates. In addition, there are some (minor) materials that are used as specialty lightweight aggregates: clay, pumice, perlite, and vermiculite.First Battle of Deep Bottom
The First Battle of Deep Bottom, also known as Darbytown, Strawberry Plains, New Market Road, or Gravel Hill, was fought July 27–29, 1864, at Deep Bottom in Henrico County, Virginia, as part of the Siege of Petersburg of the American Civil War. A Union force under Maj. Gens. Winfield S. Hancock and Philip H. Sheridan was sent on an expedition threatening Richmond, Virginia, and its railroads, intending to attract Confederate troops away from the Petersburg defensive line, in anticipation of the upcoming Battle of the Crater. The Union infantry and cavalry force was unable to break through the Confederate fortifications at Bailey's Creek and Fussell's Mill and was withdrawn, but it achieved its desired effect of momentarily reducing Confederate strength at Petersburg.Gravel pit
A gravel pit is an open-pit mine for the extraction of gravel. Gravel pits often lie in river valleys where the water table is high, so they may naturally fill with water to form ponds or lakes. Old, abandoned gravel pits are normally used either as nature reserves, or as amenity areas for water sports, landfills and walking. In addition, many gravel pits in the United Kingdom have been stocked with freshwater fish such as the common carp to create coarse fishing locations. Gravel and sand are mined for concrete, construction aggregate and other industrial mineral uses.Gravel road
A gravel road is a type of unpaved road surfaced with gravel that has been brought to the site from a quarry or stream bed. They are common in less-developed nations, and also in the rural areas of developed nations such as Canada and the United States. In New Zealand, and other Commonwealth countries, they may be known as 'metal roads'. They may be referred to as 'dirt roads' in common speech, but that term is used more for unimproved roads with no surface material added. If well constructed and maintained, a gravel road is an all-weather road.Japanese rock garden
The Japanese rock garden (枯山水, karesansui) or "dry landscape" garden, often called a zen garden, creates a miniature stylized landscape through carefully composed arrangements of rocks, water features, moss, pruned trees and bushes, and uses gravel or sand that is raked to represent ripples in water. A zen garden is usually relatively small, surrounded by a wall, and is usually meant to be seen while seated from a single viewpoint outside the garden, such as the porch of the hojo, the residence of the chief monk of the temple or monastery. Classical zen gardens were created at temples of Zen Buddhism in Kyoto during the Muromachi period. They were intended to imitate the intimate essence of nature, not its actual appearance, and to serve as an aid to meditation about the true meaning of life.Lagoon
A lagoon is a shallow body of water separated from a larger body of water by barrier islands or reefs. Lagoons are commonly divided into coastal lagoons and atoll lagoons. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as estuaries. Lagoons are common coastal features around many parts of the world.Link (Mars)
Link is a rock outcrop on the surface of Aeolis Palus, between Peace Vallis and Aeolis Mons ("Mount Sharp"), in Gale crater on the planet Mars. The outcrop was encountered by the Curiosity rover on the way from Bradbury Landing to Glenelg Intrique on September 2, 2012 (the 27th sol of the mission), and was named after a significant rock formation (and lake) in the Northwest Territories of Canada. The "approximate" site coordinates are: 4.59°S 137.44°E / -4.59; 137.44.
The outcrop is a well-sorted gravel conglomerate, containing well-rounded, smooth, abraded pebbles. Pebbles and gravel a few millimeters to centimeters across are embedded in amongst a finer, white matrix. This outcrop geology is strikingly similar to some terrestrial fluvial conglomerates. Around the rock are scattered well sorted loose gravel around 1 cm across, which are thought to be weathering out of the outcrop.
The rock has been interpreted as a cemented fluvial sediment, deposited by a "vigorously" flowing stream, probably between ankle and waist deep. This stream is part of an ancient alluvial fan, which descends from the steep terrain at the rim of Gale crater across its floor.Mike Gravel
Maurice Robert "Mike" Gravel (; born May 13, 1930) is an American politician who served as a United States Senator from Alaska from 1969 to 1981. A member of the Democratic Party, he was a candidate in the 2008 U.S. presidential election and is a candidate in the 2020 U.S. presidential election.
Born and raised in Springfield, Massachusetts, by French-Canadian immigrant parents, Gravel served in the U.S. Army in West Germany, and later graduated from the Columbia University School of General Studies. He moved to Alaska in the late 1950s, becoming a real estate developer and entering politics. He served in the Alaska House of Representatives from 1963 to 1966 and also became Speaker of the Alaska House. Gravel was elected to the U.S. Senate in 1968.
As a senator, Gravel became nationally known for his forceful but unsuccessful attempts to end the draft during the War in Vietnam and for putting the Pentagon Papers into the public record in 1971 at some risk to himself. He conducted an unusual campaign for the Democratic nomination in 1972 for Vice President of the United States, and then played a crucial role in getting Congressional approval for the Trans-Alaska pipeline in 1973. He was reelected to the Senate in 1974, but gradually alienated his Alaskan constituents, and his bid for a third term was defeated in a primary election in 1980.
Gravel returned to business ventures and went through difficult times, suffering corporate and personal bankruptcies amid poor health. He has been an advocate of direct democracy and the National Initiative. In 2006 Gravel began a run for the Democratic nomination for President of the United States to promote those ideas. His campaign gained an Internet following and national attention due to forceful, humorous, and politically unorthodox debate appearances during 2007, but he found very little support in national polls or the 2008 caucuses and primaries. In March 2008 he left the Democratic Party and joined the Libertarian Party to compete for its presidential nomination and the inclusion of the National Initiative into the Libertarian Platform. At the Libertarian National Convention of 2008 he failed on both counts. He subsequently became an executive for a marijuana products company and continued to speak out about various political issues and candidates. Gravel has announced that he is running in the 2020 Democratic primaries in order to bring his long-held policy goals to the debate stage. He officially filed to run for president on April 2, 2019.Mike Gravel 2008 presidential campaign
The 2008 presidential campaign of Mike Gravel, former Speaker of the Alaska House of Representatives and United States Senator from Alaska began on April 17, 2006 when he declared his candidacy for the Democratic nomination for President of the United States in the 2008 election, in a speech to the National Press Club.
His campaign gained an Internet following and national attention due to outspoken debate appearances during 2007, but consistently showed little support in national polls. In the 2008 Democratic caucuses and primaries, he did not win any delegates. Out of the eight candidates for the Democratic nomination for president, he received the fewest votes - less than one percent.In March 2008, Gravel announced that he had joined the Libertarian Party and would seek its presidential nomination, instead of further pursuing the Democratic nomination. In May 2008, Gravel finished fourth at the 2008 Libertarian National Convention and ended both his presidential quest and his political career, until his 2020 presidential campaign.Mike Gravel 2020 presidential campaign
The 2020 presidential campaign of Mike Gravel, former U.S. Senator from Alaska, began on March 19, 2019 with the formation of an exploratory committee, followed on April 2, 2019 with his campaign filing with the Federal Elections Commission to officially run for the presidency. His intention is not to win the nomination, but rather to push his platforms more into mainstream politics.Moraine
A moraine is any glacially formed accumulation of unconsolidated glacial debris (regolith and rock) that occurs in both currently and formerly glaciated regions on Earth (i.e. a past glacial maximum), through geomorphological processes. Moraines are formed from debris previously carried along by a glacier and normally consisting of somewhat rounded particles ranging in size from large boulders to minute glacial flour. Lateral moraines are formed at the side of the ice flow and terminal moraines at the foot, marking the maximum advance of the glacier. Other types of moraine include ground moraines, till-covered areas with irregular topography, and medial moraines which are formed where two glaciers meet.Nationwide opinion polling for the 2008 Democratic Party presidential primaries
This is a collection of scientific, public nationwide opinion polls that have been conducted relating to the 2008 Democratic presidential candidates.Quarry
A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground.
The word quarry can also include the underground quarrying for stone, such as Bath stone.Speech or Debate Clause
The Speech or Debate Clause is a clause in the United States Constitution (Article I, Section 6, Clause 1). The clause states that members of both Houses of Congress
...shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their attendance at the Session of their Respective Houses, and in going to and from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.
The intended purpose is to prevent a President or other officials of the executive branch from having members arrested on a pretext to prevent them from voting a certain way or otherwise taking actions with which the President might disagree.
A similar clause in many state constitutions protects members of state legislatures in the United States. Legislators in non-U.S. jurisdictions may be protected by a similar doctrine of parliamentary immunity.Unified Soil Classification System
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 (with the exception of Pt):
If the soil has 5–12% by weight of fines passing a #200 sieve (5% < P#200 < 12%), both grain size distribution and plasticity have a significant effect on the engineering properties of the soil, and dual notation may be used for the group symbol. For example, GW-GM corresponds to "well-graded gravel with silt."
If the soil has more than 15% by weight retained on a #4 sieve (R#4 > 15%), there is a significant amount of gravel, and the suffix "with gravel" may be added to the group name, but the group symbol does not change. For example, SP-SM could refer to "poorly graded SAND with silt" or "poorly graded SAND with silt and gravel."