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A spot height is an exact point on a map with an elevation recorded beside it that represents its height above a given datum. [1] In the UK this is the Ordnance Datum . Unlike a bench-mark , which is marked by a disc or plate, there is no official indication of a spot height on the ground although, in open country, spot heights may sometimes be ...
The term is generally applied to any item used to mark a point as an elevation reference. Frequently, bronze or aluminum disks are set in stone or concrete, or on rods driven deeply into the earth to provide a stable elevation point. If an elevation is marked on a map, but there is no physical mark on the ground, it is a spot height.
A topographical map is the main type of map used to depict elevation, often through contour lines. In a Geographic Information System (GIS), digital elevation models (DEM) are commonly used to represent the surface (topography) of a place, through a raster (grid) dataset of elevations. Digital terrain models are another way to represent terrain ...
The zero-elevation baseline or vertical datum to which a measurement of elevation or altitude is relative, e.g. the mean sea level calculated for a given location over a given period of time. [4] See also geodetic datum. de facto segregation The spatial and social separation of populations that occurs without legal sanction. [2] de jure segregation
Land surface elevation extremes by geographic region; Geographic region Highest point Maximum elevation Lowest point Minimum elevation Elevation span ⦁ Eurasia: Mount Everest, [1] China and Nepal: 8848 m 29,029 ft Dead Sea, [2] Israel, Jordan, and Palestine: −428 m −1,404 ft: 9,276 m 30,433 ft ⦁ Asia Mount Everest, [1] China and Nepal ...
It took some time for the changed definition — Liverpool to Newlyn — to work through the system: by 1950, some 40% of the lower secondary and tertiary levellings were still using the Liverpool datum. But following the Third Geodetic Levelling, Ordnance Survey maps published since March 1956 give spot heights above the Newlyn datum. [4] [5]
List of U.S. states and territories by elevation (including highest points in each U.S. state) List of highest U.S. county high points. List of highest points in California by county; List of Colorado county high points; List of highest points in Oregon by county; List of highest points in Nevada by county; List of highest points in Washington ...
Topographic maps are based on topographical surveys. Performed at large scales, these surveys are called topographical in the old sense of topography, showing a variety of elevations and landforms. [8] This is in contrast to older cadastral surveys, which primarily show property and governmental boundaries.