A quadrilateral can refer to a figure with four sides and angles in geometry, a courtyard in architecture, or a quadrangular map produced by the USGS. The USGS map divides areas into 7.5 minute rectangles, which are further divided into 16 municipalities and named after local landmarks. Quadrangles on Mars also exist.
The definition of a quadrilateral varies depending on the context. In geometry, a quadrilateral – or, more commonly, a quadrilateral – is a figure with four sides and four angles. In architecture, the term is used for a courtyard surrounded on all sides by a building. One of the most common uses of the term is to refer to a quadrangular or “quad” map, a type of map produced by the United States Geological Survey (USGS). In these maps, all areas are divided into 7.5 minute rectangles, a measure of longitude and latitude.
On a quadruple map, quadrangles appear to be rectangular, but actually have no parallel sides. On flat maps, the quadrilateral may appear as a rectangle, but on globes and globe maps, the lines vary according to the curvature of the Earth. The left and right sides of the quadrilateral have lines running up and down, or north and south; the lines are not parallel, but remain along the universally recognized longitudinal lines. The east and west lines of march run along the lines of latitude and remain parallel to each other, but are not the same length. As a result, they meet the longitudinal lines at different points.
Each quadrilateral on the USGS map ranges in area from 49 miles (78.8 km) to 70 miles (112.6 km). These squares are basic subdivisions of the USGS’s Public Land Survey System, which is used to identify parcels of land across the country. Each quadrangle on the map can be further divided into 16 different municipalities and generally extends approximately 24 miles (38.6 km) on each side.
In a quad map, the quadrangle is often named after a local land feature, such as a creek, crater, fault line, or plateau. For example, a quad in Texas is known as a “Ranger Creek, Texas quad.” It takes its name from Ranger Creek, which lies within its boundaries, and is known by that name on maps and in references.
These quadrangles, or topographical quadrangular maps, have not been limited to the Earth. They have also been established as geological maps on other planets. Quadrangles on Mars, like those in the United States and other places around the world, were named for local landmarks and identifying features.
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