U: u-shaped valley U.S. Army Corps of Engineers U.S. Congress U.S. Forest Service U.S. Soil Conservation Service ultramafic ultraviolet radiation unconformity uncorrected gravity Uniformitarianism uniformity United States Universal time University of California unsaturated zone uplift upper mantle upwelling uranium uranium-235 USGS UTC UTC-GMT conversion UTM UTM zone
U.S. Department of the Interior | U.S. Geological Survey URL: http://walrus.wr.usgs.gov/infobank/programs/html/school/U_keywords.html Page Contact: InfoBank staff Page Last Modified: Tue Dec 16 06:27:36 PST 2008 (wcs)