gravel

1. An unconsolidated mixture of rock fragments or pebbles.
2. Pathology. The sandlike granular material of urinary calculi.

1. To apply a surface of rock fragments or pebbles to.
2. To confuse; perplex.
3. Informal. To irritate.

[Middle English, from Old French gravele, diminutive of grave, pebbly shore, of Celtic origin.]

For more information on gravel, visit Britannica.com.

An unconsolidated sedimentary aggregate containing more than 50% by weight of gravel-sized particles (mean diameter greater than 0.08 in. or 2 mm). The gravel-sized particles are termed the framework; those less than 0.08 in. in diameter are the matrix. There is an important distinction between framework-supported and matrix-supported gravels. The latter may possess a muddy matrix, in which case they are termed diamictons. Typically, diamictons are unstratified internally, contain subangular framework clasts, and are deposited by mass-flow processes such as debris flow or glacial-ice transport. Water-laid gravels are typically stratified or cross-stratified and are framework-supported, with subangular to rounded clasts in a sand matrix. Less commonly, they may be sand-matrix-supported, or they may lack matrix and then are termed openwork gravels. Water-worn gravel clasts tend to conform to the shape of triaxial ellipsoids and develop preferred orientation, with long axes normal to stream flow and intermediate axes dipping gently upstream.

The consolidated equivalents of gravels are conglomerates and breccias, the latter including only angular particles. Paleoenvironmental indicators for conglomerates include stratification, size grading, particle roundness, particle orientation, and matrix–framework relations. See also Breccia; Conglomerate; Sedimentary rocks.

geology A particle size, typically 2 to 64 mm (0.787 to 2.5 in).

A loose deposit of rock fragments rounded by river erosion. The lower size limit of gravel is 2 mm but the upper limit is either 10 mm, 20 mm, 50 mm, or 60 mm according to different authorities. While river gravels are well rounded as a result of attrition, solifluction gravels, produced by freeze-thaw, are more angular. The plateau gravels of southern England are extensive deposits between 0 and 1250 m above sea level, made of flint and chert fragments in a mould of sand and clay. They were deposited by solifluction and meltwater during the Pleistocene.

A coarse granular aggregate, larger than sand; formed either naturally or by crushing rock; will pass a 76.1-mm (3-in.) sieve and be retained on a 4.76-mm (No. 4) sieve.

Calculus occurring in small particles.

For other uses, see Gravel (disambiguation).

Gravel (largest fragment in this photo is about 4 cm)

A gravel road in Terre Haute, Indiana.

Gravel being unloaded from a barge

Gravel is rock that is of a specific particle size range. Specifically, it is any loose rock that is larger than two millimeters (2 mm/0.079 in) in its smallest dimension (about 1/12 of an inch) and no more than 64 mm (2.5 in). The next smaller size class in geology is sand, which is >0.0625 to 2 mm (0.0025 to 0.0787 in) in size. The next larger size is cobble, which is >64 to 256 mm (2.5 to 10.1 in). Gravel can be sub-categorized into granule (>2 to 4 mm/0.079 to 0.16 in) and pebble (>4 to 64 mm/0.16 to 2.5 in). One 1 cu ft (28.32 dm³) of gravel typically weighs about 100 pounds (45 kg).

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-surfaced roads. Both sand and small gravel are also important for the manufacture of concrete.

Contents 1 Geological formation 1.1 Modern production 2 Etymology 3 Types 4 See also 5 References

Geological formation

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 concreted 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.

Modern production

As of 2006, the United States is the world's leading producer and consumer of gravel.^[1][2]

Etymology

The word comes from the French gravelle, meaning 'coarse sand'.

Types

Gravel with stones sized roughly between 5 and 15 millimeter.

Disused gravel pit in Lower Saxony, Germany

Multiple types of gravel have been recognized, including:

• Bank gravel: gravel intermixed with sand or clay.

• Bench gravel: a bed of gravel located on the side of a valley above the present stream bottom, indicating the former location of the stream bed when it was at a higher level.

• Creek rock: This is generally rounded, semi-polished stones, potentially of a wide range of types, that are dredged or scooped from river beds and creek beds. It is also often used as concrete aggregate and less often as a paving surface.

• Crushed Rock: Rock that is mechanically broken into small pieces then sorted by filtering through different size mesh.

• Crushed stone: This is generally limestone or dolomite that has been crushed and graded by screens to certain size classes. It is widely used in concrete and as a surfacing for roads and driveways, sometimes with tar applied over it. Crushed stone may also be made from granite and other rocks. A special type of limestone crushed stone is dense grade aggregate, or DGA, also known as crusher run. This is a mixed grade of mostly small crushed stone in a matrix of crushed limestone powder.

• Fine gravel: gravel consisting of particles with a diameter of 2 to 4 mm.

• Lag gravel: a surface accumulation of coarse gravel produced by the removal of finer particles.

• Pay gravel: also known as "pay dirt"; a nickname for gravel with a high concentration of gold and other precious metals. The metals are recovered through gold panning.

• Pea Gravel: gravel that consists of small, rounded stones used in concrete surfaces. Also used for walkways, driveways and as a substrate in home aquariums.

• Piedmont gravel: a coarse gravel carried down from high places by mountain streams and deposited on relatively flat ground, where the water runs more slowly.

• Plateau gravel: a layer of gravel on a plateau or other region above the height at which stream-terrace gravel is usually found.

• River run gravel: naturally deposited gravel found in and next to rivers and streams.

See also

• Sediment
• Construction aggregate
• Clay
• Silt
• Sand
• Pebble
• Cobble
• Boulder

References

1. ^ Mineral Commodity Summaries 2006 2009
2. ^ Industrial Sand And Gravel (Silica): World Production, By Country 2009

v • d • e Topics in geotechnical engineering Soils Clay · Silt · Sand · Gravel · Peat · Loam Soil properties Hydraulic conductivity · Water content · Void ratio · Bulk density · Thixotropy · Reynolds' dilatancy · Angle of repose · Cohesion · Porosity · Permeability · Specific storage Soil mechanics Effective stress · Pore water pressure · Shear strength · Overburden pressure · Consolidation · Soil compaction · Soil classification · Shear wave · Lateral earth pressure Geotechnical investigation Cone penetration test · Standard penetration test · Exploration geophysics · Monitoring well · Borehole Laboratory tests Atterberg limits · California bearing ratio · Direct shear test · Hydrometer · Proctor compaction test · R-value · Sieve analysis · Triaxial shear test · Hydraulic conductivity tests · Water content tests Field tests Crosshole sonic logging · Nuclear Densometer Test Foundations Bearing capacity · Shallow foundation · Deep foundation · Dynamic load testing · Wave equation analysis Retaining walls Mechanically stabilized earth · Soil nailing · Tieback · Gabion · Slurry wall Slope stability Mass wasting · Landslide · Slope stability analysis Earthquakes Soil liquefaction · Response spectrum · Seismic hazard · Ground-structure interaction Geosynthetics Geotextile · Geomembranes · Geosynthetic clay liner Instrumentation for Stability Monitoring Deformation monitoring · Automated Deformation Monitoring

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Dansk (Danish)
n. - grus, nyregrus
v. tr. - strø grus på, gruse, irritere, sætte på grund

Nederlands (Dutch)
grind, steengruis, begrinten, in verwarring brengen, irriteren

Français (French)
n. - (Constr) graviers, gravillons, (Méd) calculs
v. tr. - couvrir de gravier

Deutsch (German)
n. - Kies, Geröll, Schotter, Harngrieß, Nierensand
v. - mit Kies bestreuen, verwirren

Ελληνική (Greek)
n. - αμμοχάλικο, χαλίκι
v. - χαλικοστρώνω

Italiano (Italian)
ghiaia, renella, inghiaiare, imbarazzare

Português (Portuguese)
n. - cascalho (m), cálculo (m) (Med.)
v. - cobrir com pedregulho, embaraçar

Русский (Russian)
гравий, посыпать гравием, мочевой песок, золотоносный песок

Español (Spanish)
n. - grava, ripio, cascajo, arenillas
v. tr. - cubrir con grava, dejar perplejo a alguien

Svenska (Swedish)
n. - grus, njurgrus (med.)
v. - grusa, bringa ur fattningen, reta

中文（简体）(Chinese (Simplified))
砂砾, 砂砾层, 铺碎石, 使搁浅, 使困惑

中文（繁體）(Chinese (Traditional))
n. - 砂礫, 砂礫層
v. tr. - 鋪碎石, 使擱淺, 使困惑

한국어 (Korean)
n. - 자갈, 사력층, (병) 요결석
v. tr. - 자갈을 깔다, 난처하게 하다, 화나게 하다

日本語 (Japanese)
n. - 砂利
v. - 砂利を敷く, 当惑させる, 怒らせる

العربيه (Arabic)
‏(الاسم) حصباء او حصمه : حجارة صغيرة لتعبير الطرق (فعل) يفرش او يغطي بالحصمه‏

עברית (Hebrew)
n. - ‮חצץ, חול וחצץ, אבנים, תערובת לציפוי כבישים, אבן בכליות‬
v. tr. - ‮כיסה בחצץ, הביך‬

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