[1] Department of Geological Sciences, University of Oregon, Eugene, OR 97403, United States
[2] Department of Geology, Occidental College, Los Angeles, CA 90041, United States
[3] Coll. of Oceanic/Atmospheric Sci., Oregon State University, Corvallis, OR 97331, United States
[4] Department of Earth/Space Sciences, University of Washington, Seattle, WA 98195, United States
[5] Department of Environmental Studies, Sweet Briar College, Sweet Briar, VA 24595, United States