INTERPRETING THE GEOLOGY OF AN ICON: IGNEOUS PETROLOGY, ROCK CLIMBING, AND SCIENCE COMMUNICATION IN YOSEMITE NATIONAL PARK

The narrative of many National Parks in America is dominated by geology. To truly understand the spirit of Yosemite National Park, visitors must become acquainted with the granitic rocks that make up its iconic formations. Unfortunately, this vital part of the story of Yosemite is often overlooked as it is difficult topic for an interpretive ranger with little geologic training to communicate. We helped to address this deficit by combining petrologic mapping and science communication within the context of rock climbing. One of Yosemite’s premier icons is El Capitan - a 1 km tall cliff that displays the interior of the Sierra Nevada Batholith. Beyond exposing fascinating geology, El Capitan is at the center of global rock climbing culture and climbers from around the world come to push their limits on its soaring crack systems. Although it can be difficult for the National Park Service to draw a substantial audience with a purely geologic lecture, El Capitan commands a large pre-existing audience thanks to wide public interest in rock climbing. Each year, thousands of visitors flock to the base of El Capitan to view rock climbers, providing a unique opportunity to interpret the cliff’s geology. Recent high-resolution (decimeter scale) geologic mapping of El Capitan, completed in part by climbing, was used to develop education and outreach tools utilized by the National Park Service and the Yosemite Climbing Association to interpret fundamental concepts of geology. This project represented a unique collaboration between the Geological Society of America, the National Park Service, and the rock climbing community, and it produced valuable interpretive materials in digital, print, and narrative form. The Geological Society of America’s Geocorps program provided vital support for the creation of these materials.