AccessibilityFOIAPrivacyPolicies and Notices U.S. Department of the Interior | U.S. Geological Survey URL: https://pubs.usgs.gov/of/1999/ofr-99-0418/ Questions or Assistance: USGS Web Contact Page Last Modified: Wed Dec 7 17:01 EST 2016
U.S. Department of the Interior | U.S. Geological Survey URL: https://pubs.usgs.gov/of/1999/ofr-99-0418/ Questions or Assistance: USGS Web Contact Page Last Modified: Wed Dec 7 17:01 EST 2016