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QUARRYING

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Originally appearing in Volume V22, Page 713 of the 1911 Encyclopedia Britannica.
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QUARRYING , the See also:

art of winning or obtaining from the See also:earth's crust the various kinds of See also:stone used in construction, the operation being, in most cases, conducted in open workings. According to their See also:composition, See also:building stones are broadly classed as granites, sandstones, limestones and slates. Under the first of these heads is included a number of crystalline See also:rock See also:species, such as See also:granite, See also:syenite, See also:gneiss, &c., which to the geologist are quite distinct, but which in See also:commerce are all spoken Kinds of of as granite. They are chiefly composed of one or stone more minerals of the See also:felspar See also:group mingled with quarried- one or more of the micas or with See also:hornblende, and usually contain See also:quartz. Sandstones are chiefly composed of fragments of quartz cemented into solid rock by See also:silica and See also:oxide of See also:iron. Of these there are many varieties, including flagstone used for See also:foot-pavements, Limestones consist principally of carbonate of See also:lime. Their See also:chief See also:variations are the crystalline See also:form known as See also:marble and the See also:deposit from See also:mineral springs known as -Mexican See also:onyx. Slates are mudstones or shales hardened by See also:heat and pressure, and rendered fissile by the latter See also:agent. Chemically they consist chiefly of hydrous silicate of alumina. Theoretically, granites are massive, and have no bedding or stratification like sandstones and limestones; but all rock masses are usually found to be more or less shattered by movements of the earth's crust which occur as a result of its See also:constant readjustment to the cooling and shrinking interior, so that the rocks are divided by cracks or fissures, which are commonly known as See also:joints. In the massive granites these joints, which usually occur in two or more planes at right angles to one another, are of the greatest importance to the quarryman, as they enable him to See also:separate masses of stone with approximately parallel faces. in gneisses the parallel arrangement of the minerals usually coincides with a direction of easy cleavage,known to quarrymen as the " rift "; at right angles to this direction is usually one less easy parting, known as the " See also:grain." Sandstones and limestones are stratified rocks which have been formed as sediments in bodies of See also:water; and whether their beds are found in the normal position of horizontality, or whether they have been tilted and folded by earth movements, the direction of easiest separation is coincident with the See also:original planes of sedimentation and parallel to them. This is therefore called the " rift, " while the " grain " is at right angles to it.

In gneisses, sandstones and limestones joints also occur; and while frequently convenient for the See also:

division of the beds into masses of useful See also:size, they may be a detriment, as when they occur so See also:close together as to fall within the limits of a See also:block available for commercial purposes. In commerce the various kinds of building stone are usually designated by the name of the locality or region in which the See also:quarry is situated. In the See also:case of the more important varieties this geographic name usually conveys to the architect or builder full See also:information concerning the See also:colour, texture and other properties of the material. For example, the names Hallowell or See also:Quincy granite, See also:Medina or See also:Berea See also:sandstone, and See also:Vermont or See also:Tennessee marble, convey in the See also:United States full information to those interested. The methods of quarrying vary with the composition and hardness of the rocks, their structure, cleavage, and other See also:physical properties; also with the position and See also:character of the deposits or rock-masses. The See also:general pur- Method: employed. pose of the See also:work is to separate the material from its See also:bed in masses of form and size adapted to the intended use. Cutting the stone to accurate dimensions, dressing, rubbing and polishing are subsequent operations not involved in quarrying. The practice of quarrying consists in uncovering a sufficient See also:surface of the rock by removing superficial See also:soil, See also:sand or See also:clay, or by sinking a See also:shaft or slope, and then with proper tools and, when necessary, with See also:explosives, detaching blocks of form and size adapted to the purpose in view. Frequently the See also:outer portion of the rock has been affected by the See also:action of the See also:weather and other atmospheric agencies, so that it has become discoloured or softened by decay. This weathered material must be removed before stone can be obtained for use. A quarry should, if possible, be opened on a hillside, for in this case it is usually much easier to dispose of the water which necessarily collects in any deep excavation, and which, if drainage by gravity is not afforded, must be removed by pumping, at considerable expense.

As it is generally most convenient to operate on a See also:

vertical See also:face of rock, the preliminary work of opening a quarry is usually directed toward the See also:production of this result; but its accomplishment involves the See also:waste of a certain amount of stone, which must be broken into irregular and useless pieces. The separation of blocks of building stone is effected ordinarily by drilling holes along the outlines of the block to be removed, and then, by exploding See also:blasting-See also:powder in the holes, or by See also:driving wedges into them, exerting sufficient force to overcome the cohesion of the rock and rend it asunder. In many quarries it is found most convenient to separate a large See also:mass and afterwards See also:divide it into blocks of the required size. When the rock is stratified, or has an easily determined " rift," the holes are drilled at right angles to the See also:plane of separation. When there is no stratification or " rift," or these ratural planes of separation are too far apart, or when the position of the joints is not advantageous, a See also:row of See also:horizontal holes must be drilled Into the face or " See also:breast " of the quarry, along which separation is effected by the use of wedges. Of See also:late at certain See also:American quarries, in a granite which has no rift or direction of ready cleavage, compressed See also:air has been brought into service to effect the separation of extensive layers. A hole is drilled as deep as the desired thickness of the layer to be separated, and a small See also:charge of See also:dynamite is exploded at the bottom of it. This develops a cavity in which a small charge of powder is next exploded, producing a crack or crevice parallel to the surface of the rock. A See also:pipe for conveying compressed air is now sealed into the opening, and gradually increasing pressure is introduced. This results in the See also:gradual See also:extension of the crevice See also:developed by the See also:explosion of the powder. In the See also:absence of compressed air, of the " See also:coffin " of a See also:horse's foot; in bootmaking, to the See also:side water under pressure may be used and also small powder charges piece of See also:leather reaching from the vamp to the See also:heel. The exploded at intervals of a few days.

In thinly bedded sandstones, " See also:

quarter " of a See also:ship is the after See also:part of her side from the See also:main-where vertical joints are frequent, it is often possible to separate chains to the stern (see QUARTERDECK). the desired slabs and flagstones with crowbars and wedges, There has been much discussion as to the origin of the use of the without drilling or the use of explosives. When blasting is word " quarter " in the sense of See also:mercy, clemency, the sparing of necessary, some form of See also:gunpowder is generally used, rather the See also:life of a beaten enemy and the See also:acceptance of his surrender. than a violent explosive like dynamite, in See also:order to avoid shatter- The same use is found in Fr. quartier. See also:Cotgrave explains this word See also:ing rock. This, however, applies only See also:dimension stone. as faire See also:war, wherein souldiers are taken prisoners and ransomed g P- to at a certain See also:rate." The he real origin cannot be, as has often been When the production of broken stone for road-making, See also:concrete, repeated, following De See also:Brieux (Origins de plusieurs fagons de parler, or similar purposes is the See also:sole end in view, violent explosives are 1672), that it was due to a supposed agreement between the Dutch preferred. In limestones and See also:marbles and in the softer sand and Spaniards for ransoming See also:officers and men at one quarter of stones, channelling See also:machines, driven b See also:steam, are employed, their pay. The true source is either the See also:assignment of " quarters," g by i.e. lodgings, to captured prisoners whose lives were spared, or the by which vertical or oblique grooves or channels can be cut use of the word, now obsolete, for relations with or conduct towards with See also:great rapidity to a See also:depth of several feet. A level bed of another, often in the sense of See also:fair treatment; thus in See also:Bacon's See also:Essay rock is cleared, and on this are laid rails, along which the See also:machine on Cunning, "two, that were competitors, ...kept See also:good quarter moves. After the channels are cut, a row of holes is bored between themselves." Quarter days are the days that begin each quarter of the See also:year. perpendicular to the former at the desired distance below the In See also:England they are the 25th of See also:March (See also:Lady See also:Day), the 24th of surface of the bed, and by driving wedges into these the required See also:June (Midsummer Day), the 29th of See also:September (Michaelmas Day) blocks are separated. and the 25th of See also:December (See also:Christmas Day). They are the days When the beds of stone to be quarried are thin, and when to on which it is usually contracted that rents should be paid and houses or lands entered upon or quitted. In See also:Scotland there are remove the whole of the overlying mass of earth or rock would two legal terms, the 15th of May (See also:Whitsunday) and the uth of be too expensive, it is found convenient to treat the See also:November (Martinmas); these, together with the two conventional Mince. as if it were a mine, and to rely upon on methods terms, 2nd of See also:February (See also:Candlemas) and the 1st of See also:August (See also:Lammas), stone. quarry y P make up the Scottish quarter days.

In the Scottish burghs, however, similar to those practised in See also:

mining. A horizontal the removal terms are the 28th of May and the 28th of November. bed of rock is usually opened at its outcrop on some hillside, or In the United States the quarter days are, in See also:law, the 1st of See also:January, if this is impracticable, as shaft or slope is excavated to reach it. See also:April, See also:July and See also:October. If dimension stone is required, a deep horizontal groove is cut QUARTERDECK, the after part of the upper See also:deck of a ship. near the See also:top or the bottom of the bed. The quarry face is then In former times the upper deck of a See also:line-of-See also:battle ship or See also:frigate divided into blocks by saw-cuts, channels, or rows of See also:drill-holes, ended at the mainmast, and was connected with the forecastle and the blocks are separated by wedging or blasting. As the by two narrow passages, or gangways See also:running along the sides. excavation or stoping progresses, portions of the rock are See also:left The quarterdeck is the See also:residence and See also:symbol of authority in in See also:place as pillars to support the roof. At many localities in a warship. The starboard, or right side looking forward, is See also:Europe where roofing See also:slate is quarried, it is found in beds dipping reserved to the See also:senior officer. A sailor who had a complaint to more or less from the horizontal. These deposits are worked by make was said to come to the mainmast, because he placed stopes which follow the inclination of the bed, from which, at himself at the forward end of the quarterdeck near the See also:mast. convenient intervals, levels are driven across, to take See also:advantage According to the See also:ancient See also:custom of the See also:sea, the quarterdeck is of the cleavage of the slate. As in other subterranean quarries, to be saluted by all who come upon it, and the salute is returned pillars of rock are left to support the roof, since artificial supports by all officers See also:present.

would be more expensive. At some of the marble quarries in QUARTER SESSIONS, See also:

COURT OF, in See also:English law, the name Vermont, U.S.A., where the strata are very nearly vertical, the for the justices of the See also:peace of any See also:county, See also:riding, parts, division beds are worked to a great depth with a comparatively small or See also:liberty of a county, or of any county of a See also:city or county of a surface opening. See also:town, in general or quarter sessions assembled; it includes the See G. P. See also:Merrill, Stones for Building and Decoration (New See also:York, court of the See also:recorder of a municipal See also:borough having a separate 1898); C. Le N. See also:Foster, A See also:Text-See also:Book of Ore and Stone Mining court of quarter sessions. The word " general " in this context (See also:London and See also:Philadelphia, 1894) ; O. Herrman, Steinbruchindurtrie is contrasted with " See also:special " or " See also:petty." The court is a See also:local and Steinbruchgeologie (See also:Berlin, 1899). (F. J. H.

End of Article: QUARRYING

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