Quadrangle (geography)
Encyclopedia
In geology or geography, the word "quadrangle" usually refers to a United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 (USGS) 7.5-minute quadrangle map, which are usually named after a local physiographic feature. The shorthand "quad" is also used, especially with the name of the map; for example, "the Ranger Creek, Texas quad map". These maps appear rectangular, hence the use of the word "quadrangle" to describe them. On a USGS 7.5-minute quadrangle map, the north and south limits of the quadrangle are not straight lines, but are actually curved to match Earth's lines of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 on the standard projection. The east and west limits are usually not parallel as they match Earth's lines of longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

. In the United States, a 7.5 minute quadrangle map covers an area of 49 to 70 square miles.

As a specific surveying term, a quadrangle is the basic subdivision of the United States Public Land Survey System
Public Land Survey System
The Public Land Survey System is a method used in the United States to survey and identify land parcels, particularly for titles and deeds of rural, wild or undeveloped land. Its basic units of area are the township and section. It is sometimes referred to as the rectangular survey system,...

. In this system, a quadrangle is an area that can be subdivided into 16 township
Township
The word township is used to refer to different kinds of settlements in different countries. Township is generally associated with an urban area. However there are many exceptions to this rule. In Australia, the United States, and Canada, they may be settlements too small to be considered urban...

s, and has limits generally measuring 24 miles (38.6 km) on each side, although this distance is not exact due to the effects of surveying and mapping the curved surface of Earth.

The surfaces of other planets have also been divided into quadrangles by the USGS. Martian quadrangles are also named after local features.

Quadrangles that lie on the pole of a body are also sometimes called "areas" instead, since they are circular rather than four-sided.

See also

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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