1970. United State. Geological Survey. This data set originated as a Digital Raster Graphic (DRG) produced from a scanned USGS topographic map. The DRG included the collar information an... United State. Geological Survey.
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1992. United State. Geological Survey. This data set contain a black and white digital image taken in 1992 which covers most of Arizona. The image was constructed by combining multiple f... United State. Geological Survey.