Participants gathered at the base of the 22-Ma Harmony Hills Tuff, one of the regionally extensive ash-flow tuffs that constrain emplacement parameters and timing of the MGS and SGS. From left to right: Shannon Hunter, Bill Lund, Chris Rowan, Julia Morgan, Grant Willis, Nic Barth, Lee Siebert, Jay Melosh, Eric Ferré, Bob Biek, Kevin Rafferty, Sam Thiele, Mike Hozik, Mark Anders, Zach Smith, Ashley Griffith, Scott Giorgis, Majie Fan, Troy Barber, Melanie Ray, Jeff Keith, Dave Malone, Pete Rowley, Mike Braunagel, David Hacker, and Collin Jensen (Amy Hughes is not pictured). Photo courtesy Lance Weaver, Utah Geological Survey.