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Cofrin Center for Biodiversity

•  BLOCKS & QUADRANGLES  •

By law the US Geological Survey is the nation's cartographer. Many of their programs employ the concept of a "quadrangle" to define the extent that is shown on a map. Quadrangles are simply areas on the earth's surface bounded by lines of latitude and longitude. USGS quadrangles are the basis of several map tiling schemes that are used extensively for paper maps and spatially referenced digital data.

One-Degree Blocks
A list of the one-degree blocks intersected by a project footprint is essential project planning information. One-degree blocks are quadrangles whose boundaries are whole-number lines of latitude and longitude. They span one degree south to north and one degree east to west. Names consist of a five-character code derived from the coordinates of the southeast corner. Information for the block that includes the UW-Green Bay campus is as follows:

  • South to north extent: 44° to 45° north
  • East to west extent: 87° to 88° west
  • Block name: 44087

7½ Minute Quadrangles
A list of the 7½ minute quadrangles intersected by a project footprint is essential project planning information. 7½ minute quadrangles result when a one-degree block is divided into 8 rows and 8 columns of equal-size tiles (one-eighth degree = 7½ minutes). They are identified by name and by USGS Id. Information for the quadrangle that includes the UW-Green Bay campus is as follows:

  • South to north extent: 44° 30' to 44° 37½' north
  • East to west extent: 87° 52½' to 88° 0' west
  • Quadrangle name: Green Bay East
  • Quadrangle id: 44087e8