(2019) Fieldtrip booklet for GSA Grand Canyon Thompson Field Forum I, "Age and Carving of Grand Canyon: Towards a resolution of 150 years of debate" (September 14-21, 2019)

<p class="MsoNoSpacing">Booklet containing USGS Grand Canyon Geologic River Maps.</p> <p class="MsoNoSpacing"><b>The Conveners for the 2019 GSA Thompson Field Forum were </b>Karl Karlstrom and Laura Crossey, University of New Mexico, Eugene Humphreys, University of Oregon, David Shuster, University of California Berkeley, and Kelin Whipple, Arizona State University.</p> <p class="MsoNoSpacing">The age and evolution of the 1.6-km-deep, 270-mile-long Grand Canyon have been debated since J.W. Powell's exploration of the Colorado River in 1869. This GSA Thompson Field Forum honored the 150^th anniversary of Powell's trip. It involved 28 researchers and young scientists who discussed the evidence for the age and incision history of Grand Canyon in the context of recent advances and ongoing debates. The objective was to promote a next generation of research on the evolution and tectonic geomorphology of this iconic region, as well as similar studies globally, and debate the evidence for and against mantle-driven dynamic topography. The field forum started and ended in Las Vegas, Nevada, USA, and was run under a charter with Grand Canyon Expeditions. The eight-day river trip covered 280 river miles from Lees Ferry to Pearce Ferry. Each participant gave a short seminar as discussions on the outcrop, "plenary" discussions at morning and evening seminars, or short talks and discussions on boats while floating past key areas. This booklet became known as "the hymnal"; each participnat had one in a waterproof bag and their pages, sent in ahead of time by each participant, served as the "slides" for the river seminars.</p>