In geology or geography, the word "quadrangle" usually refers to a United States Geological Survey (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 are one-quarter of the older 15-minute series. On a 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 on the standard projection. The east and west limits are usually not parallel as they match Earth's lines of longitude. In the United States, a 7.5 minute quadrangle map covers an area of .