Affiliation: | U.S. Geological Survey, 400 S. Clinton St., Iowa City, IA 52244;(319) 358-3614;fax (319) 358-3606;;U.S. Geological Survey, 1201 Pacific Ave., Ste. 600, Tacoma, WA 98402;U.S. Geological Survey, Placer Hall, 6000 J St., Sacramento, CA 95819 |