GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 75-12
Presentation Time: 11:15 AM


KARLSTROM, Karl E., Earth and Planetary Sciences, UNM, Albuquerque, 87131, CROSSEY, Laura J., Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, SEMKEN, Steven, School of Earth and Space Exploration and Center for Education through Exploration, Arizona State University, PO Box 871404, Tempe, AZ 85287-1404, CROW, Ryan, U.S. Geological Survey, 2255 N Gemini Dr. 86001, Flagstaff, AZ 86001 and WILLIAMS, Michael L., Department of Geosciences, University of Massachusetts Amherst, 611 N Pleasant St, Amherst, MA 01003

Grand Canyon National Park is globally important as a research laboratory, and for informal geoscience education for 6-7 million annual visitors. Over the past 100-150 years, Grand Canyon has become iconic in the realms of science, art, policy, and many other forms of human inspiration. The Trail of Time Exhibition is a 4.6-km-long timeline trail on the South Rim marked off at 1 meter = 1 million years. Grand Canyon’s rocks are displayed at their birthdays along the timeline with wayside signs and viewing tubes to help connect vistas to concepts. We proposed the concept to the Park in 1995, it was funded by NSF in 2006, and it opened in 2010. One now hears geology discussed in diverse languages along the Trial. Our goal in creating the exhibit was to provide dynamic pathways between research advances, ethnogeoscience, effective geoscience education, public science literacy, and Park resource management. Examples of research advances and how we try to convey them are as follows. 1) Our continent was formed by amalgamation of island arcs as recorded in the 1.84-1.66 Ga basement rocks. 2) Grand Canyon Supergroup preserves 2 basinal successions, 1.25 Ga- 1.1 Ga Unkar and 775 to 729 Ma Chuar groups, that formed in the continental interior during assembly and breakup of the supercontinent of Rodinia, with correlatives in Australia. 3) Great Unconformities mark huge erosion and more time “missing” than recorded in the past 2 billion years. 4) Tonto Group stratigraphy is redefined by new dating; it records rapid (508-500 Ma) advance of seas across North American and other continents. 5) Grand Canyon was carved in the past 5 Ma as the Colorado River found its way from the Rockies, utilizing older paleocanyons, to reach the opening Gulf of California about 4.8 Ma. 6) Lavas flowed into and dammed the Colorado River more than 17 times, some dams bursting within a few thousand years, hinting at the future fate of today’s man-made dams. 7) N-Rim and S-Rim waters have distinct stable isotope signatures and, along with other natural and artificial tracers, define groundwater mixing and complex fault and karst pathways for groundwaters. Future meetings that bring researchers, educators, interpreters, and resource managers together, like the one held April 18-20, 2019, are recommended to stimulate new efforts that can build on Trail of Time concepts.