- Industry: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
A map showing primarily political or social data such as political divisions, populations or occupations.
Industry:Earth science
(1) A plain formed by the deposition of alluvium, usually adjacent to a river which overflows periodically. (2) A level region bordering a river and formed by the deposition of material (usually sand and silt) which the river has carried in suspension.
Industry:Earth science
The equatorial horizontal parallax of a celestial body at the average geocentric distance of that body. This quantity differs significantly from the equatorial horizontal parallax only for bodies within the Solar System.
Industry:Earth science
A rhombic prism of natural calcite, cut into two equal parts along a diagonal plane and the two parts then cemented together with Canadan balsam; the dihedral angles opposite the cemented faces are ground to 68<sup>o</sup>. Light entering the small (end) face of the rhomb parallel to the long edge is split into two rays, one of which is linearly polarized and passes straight through the prism, while the other is lost to total reflection. The Nicol prism is used for producing linearly polarized light and for discriminating against light that is linearly polarized in other directions.
Industry:Earth science
(1) A map projection, from a sphere to a cylinder, mapping meridians into equally spaced straight lines and parallels of latitude into equally spaced, straight lines perpendicular to the lines representing meridians. (2) A map projection similar to that defined above, but mapping the rotational ellipsoid onto a cylinder. The two principal forms are the Plate Carrée map projection, in which spacing is the same for the two families of lines, and the modified (equi-rectangular) Plate Carrée map projection, which uses different spacings for the two families. (3) A map projection similar to that defined in (1) or (2), but with the axis of the cylinder inclined at an angle to the polar axis of the ellipsoid.
Industry:Earth science
(1) A place where gold is obtained by washing out the metal from its admixture with sand or gravel. (2) An alluvial or glacial deposited, as of sand or gravel, containing particles of gold or other valuable mineral. In mining law of the United States of America, mineral deposits (not veins in place) are treated as placers, so far as locating, holding and patenting are concerned. Various minerals, besides metallic ores, have been held to fall under this provision, but not coal, oil or salt.
Industry:Earth science
A narrow, navigable pass or channel between two landmasses or shoals.
Industry:Earth science
The condition in which one curve is tangent to another at a point. The term is frequently used in celestial mechanics to denote the tangency of a particular ellipse to the actual path of a satellite.
Industry:Earth science
(1) The difference between the direction from a point on the surface of the Earth to a celestial object, and the direction from the center of the Earth to the same object. (2) The difference between the direction from a point on the surface of a rotational ellipsoid representing the Earth to a celestial object, and the direction from the center of that ellipsoid to the same object. (3) The angle subtended, at a celestial object, by the line from a specified point on the Earth (or on a specified rotational ellipsoid) to the center of the Earth (or to the center of that ellipsoid). Diurnal parallax is also called daily parallax and geocentric parallax. It is equal to the horizontal parallax when the celestial object is on a horizontal plane through the observer. It is equal to the equatorial horizontal parallax when the observer is, at the same time, on the equator. The coordinates given in ephemerides for celestial bodies within the Solar System have usually been derived from observations by applying a correction for diurnal parallax. Such a correction for the parallax of a body outside the Solar System is insignificant.
Industry:Earth science
