1. Ecological Restoration Institute, Box 15017, Northern Arizona University, Flagstaff AZ 86011, USA; Quaternary Sciences Program, Box 5644, Northern Arizona University, Flagstaff AZ 86011, USA
2. Center for Environmental Sciences & Education, Box 5964, Northern Arizona University, Flagstaff AZ 86011, USA; Quaternary Sciences Program, Box 5644, Northern Arizona University, Flagstaff AZ 86011, USA
3. Department of Earth Sciences, Box 173480, Montana State University, Bozeman MT 59717, USA