title: Response to Comments on "Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon".
abstract: We reiterate that geological observations do not require Grand Canyon carving coeval with Colorado River integration. (U-Th)/He data from the western canyon, totaling 29 reproducible analyses from six samples and two labs, compellingly support an ancient canyon. Three dispersed analyses from one anomalous sample do not refute this conclusion, nor do the claimed shortcomings of our modeling have validity.
authors.affiliation: Department of Geological Sciences, University of Colorado at Boulder, 2200 Colorado Avenue, UCB 399, Boulder, CO 80309, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Flowers
authors.forename: K A
authors.initials: KA
authors.lastname: Farley