quadrangle (geography)

{{short description|Large area in geology or geography}}

{{More citations needed|date=October 2022}}

File:Mount Marcy New York USGS topo map 1892.jpg

A "quadrangle" is a topographic map produced by the United States Geological Survey (USGS) covering the United States. 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 longitude.

From approximately 1947–1992, the USGS produced the 7.5 minute series, with each map covering an area one-quarter of the older 15-minute quad series, which it replaced.{{cite web |title=Topographic Maps |url=https://www.usgs.gov/core-science-systems/national-geospatial-program/topographic-maps |publisher=United States Geological Survey |access-date=4 April 2020}} A 7.5 minute quadrangle map covers an area of {{convert|49|to|70|sqmi|km2}}.[http://pubs.usgs.gov/fs/2002/0015/ Map Scales, Fact Sheet FS105-02, (February 2002)] Both map series were produced via photogrammetric analysis of aerial photography using stereoplotters supplemented by field surveys. These maps employ the 1927 North American Datum (NAD27); conversion or a change in settings is necessary when using a GPS which by default employ the WGS84 geodetic datum. Beginning in 2009, the USGS made available digital versions of 7.5 minute quadrangle maps based on GIS data that use the NAD83 datum, which is typically within one meter of WGS84, or within the uncertainty of most GPS coordinate measurements. The USGS also produces quarter quadrangle (QQ) maps of areas 3.75 minutes square.{{cite web|title=Quarter Quad of Digital Orthophoto Quadrangle (DOQs) Color|url=https://www.usgs.gov/media/images/quarter-quad-digital-orthophoto-quadrangle-doqs-color|access-date=2023-01-01}}{{cite web|title=USGS 3.75 minute quarter quadrangle boundaries|url=https://data.austintexas.gov/Locations-and-Maps/USGS-3-75-minute-quarter-quadrangle-boundaries/8r3c-cnbt|access-date=2023-01-01}}{{cite web|title=3.75' 1:12,000 Quarter Quadrangle Index|url=https://catalog.data.gov/dataset/3-75039-1-12000-quarter-quadrangle-index|archive-url=https://web.archive.org/web/20201023074256/https://catalog.data.gov/dataset/3-75039-1-12000-quarter-quadrangle-index |access-date=2023-01-01|archive-date=2020-10-23 }}

The surfaces of other planets have also been divided into quadrangles by the USGS. Martian quadrangles are also named after local features.{{cite book| title=Mapping Mars: Science, Imagination, and the Birth of a World| first=Oliver| last=Morton| publisher=Picador USA| location=New York| year=2002| isbn=0-312-24551-3| pages=[https://archive.org/details/mappingmarsscien00mort_0/page/98 98]| url-access=registration| url=https://archive.org/details/mappingmarsscien00mort_0}}