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The various features shown on the map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads. These signs are usually explained in the margin of the map, or on a separately published characteristic sheet. [17] [18] [19] Topographic maps are also commonly called contour maps or ...
The maps are usually named after local physiographic features. The shorthand "quad" is also used, especially with the name of the map; for example, "the Ranger Creek, Texas quad". A quadrangle is defined by north and south boundaries of constant latitude (which are not great circles so are curved), and by east and west boundaries of constant ...
DOQs produced by the USGS cover an area measuring 7.5-minutes longitude by 7.5-minutes latitude (the same area covered by a USGS 1:24,000-scale topographic map, also known as a 7.5-minute quadrangle) or 3.75-minutes by 3.75-minutes.
The largest (both in terms of scale and quantity) and best-known topographic series is the 7.5-minute, 1:24,000 scale, quadrangle, a non-metric scale virtually unique to the United States. Each of these maps covers an area bounded by two lines of latitude and two lines of longitude spaced 7.5 minutes apart.
1 Clarify the discussion of map scale by introducing the idea of point scale using the Mercator projections as examples. 2 Contrast map point scale and RF, the representative fraction for the map. The former is a function of position. The latter is constant over the whole map. 3 Remove some of the trivial examples. 4 Remove all the the non-map ...
These 1:25,000 scale maps were produced from the 1960s to about 1975, then abandoned, and liquidated in the 1980s (along with the scattered coverage of the 1:500,000 and 1:125,000 scale). Most were quadrangles of 7.5' by 7.5', but two unusually-shaped coverages were provided to cover Whitehorse, one being primarily 105 D/11 h but with portions ...
All magnitude scales retain the logarithmic scale as devised by Charles Richter, and are adjusted so the mid-range approximately correlates with the original "Richter" scale. [8] Most magnitude scales are based on measurements of only part of an earthquake's seismic wave-train, and therefore are incomplete.
In most European countries, the largest scale topographic map series is a 1:25.000 scale series. Notable exceptions are Austria (1:50,000) and Finland (1:20,000). Many non-European states limit the largest scale of their map series, usually to 1:50,000 scale, frequently due to the large size of the country covered (and hence for financial reasons).