1. U.S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, Alaska 99508, USA
2. Retired, U.S. Geological Survey, Anchorage, Alaska 99508, USA
3. U.S. Geological Survey, Spokane, Washington 99201, USA
4. GeoSep Services, 1521 Pine Cone Road, Moscow, Idaho 83843, USA