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Digging, also referred to asexcavation, is the process of using some implement such asclaws,hands, manualtools orheavy equipment, to remove material from a solid surface, usuallysoil,sand orrock on the surface ofEarth. Digging is actually the combination of two processes, the first being the breaking orcutting of the surface, and the second being the removal and relocation of the material found there.[1] In a simple digging situation, this may be accomplished in a single motion, with the digging implement being used to break the surface and immediately fling the material away from the hole or other structure being dug.
Many kinds of animals engage in digging, either as part ofburrowing behavior or to search forfood orwater under the surface of the ground.[2] Historically, humans have engaged in digging for both of these reasons, and for a variety of additional reasons, such as engaging inagriculture andgardening, searching forminerals,metals, and otherraw materials such as duringmining andquarrying, preparing forconstruction, makingfortifications andirrigation, and alsoexcavations inarchaeology, searching forfossils and rocks inpalaeontology andgeology andburial of the dead.
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There are a wide variety of reasons for which humans digholes,trenches, and other subsurface structures. It has long been observed that humans have a seemingly instinctive desire to dig holes in the ground, manifesting inchildhood.[3]
Like other animals, humans dig in the ground to find food and water. Wood-linedwater wells are known from the early NeolithicLinear Pottery culture, for example in Kückhoven (an outlying centre ofErkelenz), dated 5090 BC andEythra, dated 5200 BC in Schletz (an outlying centre ofAsparn an der Zaya) inAustria.[4] Humans are unique among animals in the practice ofburial of the dead. Intentional burial, particularly withgrave goods, may be one of the earliest detectable forms of religious practice since, asPhilip Lieberman suggests, it may signify a "concern for the dead that transcends daily life".[5] Evidence suggests that theNeanderthals were the firsthuman species to practice burial behavior and intentionally bury their dead, doing so in shallow graves along with stone tools and animal bones.[6][7] Exemplary sites includeShanidar in Iraq,Kebara Cave in Israel andKrapina in Croatia. Some scholars, however, argue that these bodies may have been disposed of forsecular reasons.[8] Notably, burial of the dead prevents diseases associated with the presence of corpses, and preventsscavengers and other predators from being attracted.
The earliest undisputedhuman burial discovered so far dates back 100,000 years. Human skeletal remains stained withred ochre were discovered in the Skhul cave atQafzeh, Israel. A variety of grave goods were present at the site, including the mandible of a wild boar in the arms of one of the skeletons.[9]
As human technology advanced, digging began to be used foragriculture,mining, and inearthworks, and new techniques and technologies were developed to suit these purposes.
Inconstruction andcivil engineering, aborrow pit, also known as a sand box, is an area where material (usuallysoil,gravel orsand) has been dug for use at another location.[10] Borrow pits can be found close to many major construction projects. For example, soil might be excavated tofill an embankment for ahighway,clay might be excavated for use inbrick-making, gravel to be used for makingconcrete, etc.
In some cases, the borrow pits may become filled withground water, formingrecreational areas or sustainablewildlifehabitats (one such example is the Merton Borrow Pit, nearOxford in centralEngland, excavated to provide materials for the nearbyM40 motorway). In other cases, borrow pits may be used forlandfill andwaste disposal.
Borrow pits are common archaeological features inWaikato, where sand and gravel were dug to mix with clay topsoils to improve their drainage and friability,[11] to suit growth ofkūmara andtaro, brought byMāori from tropical islands.[12]
A regional variation of this is termed "barrow pit" in the western United States (especially the Rocky Mountains). The localism—sometimes pronounced "borrer pit"—describes the ditch along a roadway. These ditches were excavated to provide the fill to level and crown the roadway and subsequently provided drainage for the road.[13]
Anexcavation lake (also aflooded gravel pit) is an artificiallake, which usually has its origins in the excavation ofgravel orsand for construction materials or in some other kind ofsurface mining. In many cases, the excavation holes are landscaped according to theland restoration required by law. Because the excavation reached a point below thewater table, lakes form naturally. Less frequently, excavation lakes are intentionally made, especially asrecreation areas.
In Germany and Austria the lakes are almost always used for fishing, since a fishery is created by law with every surface water. At some excavation lakes, beaches are added for swimming or otherwater sports, in particular boating, water skiing or windsurfing. To support these uses, large parking lots, changing areas, and eating areas are also set up. In some cases, the excavation lake serves as a nature reserve, as in the case of the lakes in theAttenborough Nature Reserve.
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Although humans are capable of digging in sand and soil using their bare hands, digging is often more easily accomplished with tools. The most basic tool for digging is theshovel.[1] InNeolithic times and earlier, a large animal'sscapula (shoulder blade) was often used as a crude shovel.[14] In modern times, shovels are typically made of metal, with a wooden handle. Because digging is a cutting process, particularly where the soil being dug contains plantroots, digging is aided by the shovel being sharpened.[15]
Historically, manual shoveling (often in combination withpicking) was the chief means of excavation in construction,mining, andquarrying, and digging projects employed large numbers of people. After theIndustrial Revolution,mechanization viasteam shovels and laterhydraulic equipment (excavators such asbackhoes andloaders) gradually replaced most manual shoveling; however, individual homeowners still often find reasons to engage in manual digging during smaller-scale projects around the home.[1] Different methods of digging can also result in different excavation depth and force, potentially risking exposure or damage to subsurface pipelines and wiring. In the United States and Canada, homeowners and contractors are required to notify a utility-run call center before digging to ensure they do not strike buried utilities and infrastructure.[16]
Theexcavatability of an earth (rock andregolith) material is a measure of the material to be excavated (dug) with conventional excavation equipment such as abulldozer withrippers,backhoe,scraper and other grading equipment. Materials that cannot be excavated with conventional excavation equipment are said to be non-rippable. Such material typically requires pre-blasting or use of percussion hammers or chisels to facilitate excavation. The excavatability orrippability of earth materials is evaluated typically by ageophysicist,engineering geologist, orgeotechnical engineer.
Therippability of an earth (rock) material is a measure of its ability to be excavated with conventional excavation equipment.[17] A material may be classified as rippable, marginally rippable or non-rippable. The rippability of a material is often evaluated by anengineering geologist and/orgeophysicist utilizing theseismic refraction equipment (seerefraction).[18][19] Rippability studies can involve the performance ofseismic refraction traverses, the drilling ofborings with an air percussion drill rig, the excavation of test trenches with a bulldozer with rippers or backhoe, and by geologic mapping.
Cave-in of an excavation is the detachment of the mass of soil in the side of thetrench and its displacement into the hole, which represents ahazard to the person inside.[20][21] Cave-ins are considered the largest risk when working within trenches.[22][23][24] Cave-ins can be caused by a combination of pressure on soil,vibration from equipment, and excessive loads. Several techniques are used to minimize the likelihood of cave-ins, including sloping,shoring andshielding.[25]
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Authority control databases: National |
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