CHE, Yueyi, Earth and Planetary Sciences Department, Stanford University, 736 Escondido Rd, Apt 434, Stanford, CA 94305, ABBEY, Alyssa, Department of Geological Sciences, California State University Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840, SHUSTER, David, Earth and Planetary Science Department, University of California, Berkeley, Berkeley, CA 94720-4767, BALCO, Greg, Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, STOCK, Greg M., National Park Service, Yosemite National Park, El Portal, CA 95318 and CUFFEY, Kurt M., Department of Geography, University of California, Berkeley, Berkeley, CA 94720