GEOLOGICAL DEFINITIONS.Manyterms, in general use among scientific men, and usually employed in agricultural works, are obscure to young readers. For their sakes we will explain some of them; and shall not be angry ifoldmen profit by the explanation.Soil.—The surface-earth, of whatever ingredients it may be composed. It may be a clay-soil, a sand-soil, a calcareous soil, as the surface is composed of clay, or sand, or clay strongly mixed with lime, etc.Subsoil.—The earth lying below the ordinary depth to which the plow or spade penetrate. Sometimes it has hardened by the running of the plow over it for a series of years; then it is calledpan, as hard-pan, clay-pan, etc. It is sometimes of the same nature as the top-soil, as in clay-lands; in others it is a different earth; as when a coarse gravel underlies vegetable mold, or when clay lies beneath sandy soil.Subsoil Plowing.—In ordinary plowing, the share runs from five to seven inches deep. A plow has been constructed (called subsoil plow), to follow in the furrow, and break up from six to eight inches deeper—so that the whole plowing penetrates from ten to sixteen inches.Subsoil Plow.—A plow having a narrow “double share, or a small share on each side of the coulter, and no mold-board.” It is designed to break up and soften the subsoil, but not to bring it up to the top.Mold.—A soil in which decayed vegetable matter largely predominates overearths. Thus, leaf-mold is soilprincipallycomposed of rotten leaves; dung-mold, of dung reduced to a fine powdery matter; heath-mold, a black vegetable soil found in heath-lands; peat-mold, forest-mold, garden-mold, etc.Loam.—Clay, or any of the primitive earths, reduced to a mellow, friable state by intermixture ofsand, or vegetablematter, is called loam. Clay lands well manured with sand, dung, or muck, are turned, gradually, to a loam.Argillaceous.—From the Latin (argillaceus,) soil principally composed of clay.Alumina or Alumine.—Generally employed to signifypureclay. It is, chemically speaking, a metallic oxide;aluminiumis the metallicbase, and is an elementary substance.It is generally known that thediamondis pure carbon (charcoal is carbon in an impure state), but it is not as generally known that therubyand thesapphire, “two of the most beautiful gems with which we are acquainted, are composed almost solely of alumina,” or pure clay in a crystallized state.Silicious.—An earth composed largely of silex.Silexorsilicais considered to be a primitive earth constituting flint, and containing most kinds of sands, and sandstones, etc. China or porcelain, ware is formed from silica and alumina united,i. e.from silicious sand and clay.Calcareous.—A soil into the composition of which lime enters largely. Limestone lands are calcareous. Pure clay manured freely with marl becomes calcareous, for marl is, mostly, clay and carbonate of lime.Alluvial.—Strictly speaking, alluvium or our alluvial soil, is a soil formed by causes yet in existence. Thus a bottom-land is formed by the wash of a river. It is usually a mixture of decayed vegetable matter and sand.Diluvial.—A diluvial soil or deposit is one formed by causes no longer in existence. Thus a deposit by a deluge is termeddiluvial. The word is derived from the Latin (diluvium), signifying a deluge.The terms argillaceous, calcareous, silicious, alluvial and diluvial are constantly employed in all works which treat of husbandry.Friable.—A friable soil is one which crumbles easily. Clay isadhesive, or in common languageclammy: leaf-moldis friable, or crumbling. Clay becomes friable when, by exposure to air or frost, or by addition of sand, vegetable matter, etc., it is thoroughly mellowed.
Manyterms, in general use among scientific men, and usually employed in agricultural works, are obscure to young readers. For their sakes we will explain some of them; and shall not be angry ifoldmen profit by the explanation.
Soil.—The surface-earth, of whatever ingredients it may be composed. It may be a clay-soil, a sand-soil, a calcareous soil, as the surface is composed of clay, or sand, or clay strongly mixed with lime, etc.
Subsoil.—The earth lying below the ordinary depth to which the plow or spade penetrate. Sometimes it has hardened by the running of the plow over it for a series of years; then it is calledpan, as hard-pan, clay-pan, etc. It is sometimes of the same nature as the top-soil, as in clay-lands; in others it is a different earth; as when a coarse gravel underlies vegetable mold, or when clay lies beneath sandy soil.
Subsoil Plowing.—In ordinary plowing, the share runs from five to seven inches deep. A plow has been constructed (called subsoil plow), to follow in the furrow, and break up from six to eight inches deeper—so that the whole plowing penetrates from ten to sixteen inches.
Subsoil Plow.—A plow having a narrow “double share, or a small share on each side of the coulter, and no mold-board.” It is designed to break up and soften the subsoil, but not to bring it up to the top.
Mold.—A soil in which decayed vegetable matter largely predominates overearths. Thus, leaf-mold is soilprincipallycomposed of rotten leaves; dung-mold, of dung reduced to a fine powdery matter; heath-mold, a black vegetable soil found in heath-lands; peat-mold, forest-mold, garden-mold, etc.
Loam.—Clay, or any of the primitive earths, reduced to a mellow, friable state by intermixture ofsand, or vegetablematter, is called loam. Clay lands well manured with sand, dung, or muck, are turned, gradually, to a loam.
Argillaceous.—From the Latin (argillaceus,) soil principally composed of clay.
Alumina or Alumine.—Generally employed to signifypureclay. It is, chemically speaking, a metallic oxide;aluminiumis the metallicbase, and is an elementary substance.
It is generally known that thediamondis pure carbon (charcoal is carbon in an impure state), but it is not as generally known that therubyand thesapphire, “two of the most beautiful gems with which we are acquainted, are composed almost solely of alumina,” or pure clay in a crystallized state.
Silicious.—An earth composed largely of silex.Silexorsilicais considered to be a primitive earth constituting flint, and containing most kinds of sands, and sandstones, etc. China or porcelain, ware is formed from silica and alumina united,i. e.from silicious sand and clay.
Calcareous.—A soil into the composition of which lime enters largely. Limestone lands are calcareous. Pure clay manured freely with marl becomes calcareous, for marl is, mostly, clay and carbonate of lime.
Alluvial.—Strictly speaking, alluvium or our alluvial soil, is a soil formed by causes yet in existence. Thus a bottom-land is formed by the wash of a river. It is usually a mixture of decayed vegetable matter and sand.
Diluvial.—A diluvial soil or deposit is one formed by causes no longer in existence. Thus a deposit by a deluge is termeddiluvial. The word is derived from the Latin (diluvium), signifying a deluge.
The terms argillaceous, calcareous, silicious, alluvial and diluvial are constantly employed in all works which treat of husbandry.
Friable.—A friable soil is one which crumbles easily. Clay isadhesive, or in common languageclammy: leaf-moldis friable, or crumbling. Clay becomes friable when, by exposure to air or frost, or by addition of sand, vegetable matter, etc., it is thoroughly mellowed.