Navajo Loop Trail Rock Fall Update
Contact: Kristin Legg, 435-834-4900
Bryce Canyon Studies Navajo Loop Trail Rock fall
On November 7, 2006, Bryce Canyon National Park staff teamed up with professors from Southern Utah University (SUU) to explore alternatives for the rock slide that occurred on the Wall Street side of the Navajo Loop Trail in May 2006. There was wide agreement that this rock slide has significant scientific and research value since the exact time is known when it occurred. The rock slide also provides a unique opportunity to explain to visitors about erosion at Bryce Canyon.
The team discussed a number of strategies to monitor the rock fall. Monitoring could entail something as simple as repeat photography to using a total station to survey the entire rock fall. In the future, the park may look into using ground laser surveys (LIDAR) to measure erosion rates. Dr. Blair McDonald, Associate Professor of Engineering, is using this opportunity to survey the rock fall with students in a lab class on survey techniques. The information compiled by the class will provide the park with a baseline to compare surveys collected in the spring. The joint effort between the National Park Service and SUU is one example of how the Alliance for Education, Memorandum of Understanding that was established in July 2006 is in use.
The Wall Street side of the trail will remain closed from the top throughout the winter to ensure visitor safety as the park develops a plan to reopen the trail, complete environmental compliance, and obtain funding. This will also allow freeze-thaw and spring run-off to further settle the pile, fill voids, and bring down more material that may be loose, minimize work that has to be done and redone, and monitor the rock pile. The monitoring will provide information to management in order to make a decision on what should be done with this section of trail. The park is exploring a number of different options for the trail, including: 1) devising a safe way for visitors to traverse the pile allowing access through Wall Street while interpreting this geologic event and allow for continued monitoring of the geologic processes, 2) removing the rock pile and restoring the slot canyon to pre-rock fall conditions, which would limit the interpretive and research opportunities, 3) preserving the pile for interpretation and monitoring of geologic processes while keeping this section of trail closed, or 4) some combination of the above.
The rock fall was caused by the same processes, mainly weathering and erosion, which have shaped Bryce Canyon into what visitors see today. The primary weathering force at Bryce Canyon is frost wedging. Here, we experience over 200 freeze/thaw cycles each year. Water or melting snow seeps into the cracks of rocks during the day and at night the water freezes. When water freezes it expands by almost 10%, exerting tremendous pressure on the adjacent rocks. Bit by bit, cracks are pried open ever wider, in the same way a pothole forms in a paved road. In addition to frost wedging, rain also sculpts the landscape. Even the crystal clear air of Bryce Canyon creates slightly acidic rainwater. This weak carbonic acid can slowly dissolve limestone grain by grain. Rain is also a source of erosion. In the summer, monsoonal rainstorms travel through the Bryce Canyon region bringing short duration, high intensity rain causing the relocation of rock and soil debris.
All other trails in the park remain open at this time. Visitors are still able to complete a loop between Sunrise and Sunset Points by connecting the Queens Garden Trail with the Two Bridges side of the Navajo Loop Trail. The Queens Garden Trail had extensive repair work on it over the summer and remains in good condition despite a wet October.
Be prepared for hiking at Bryce Canyon. Wear sturdy hiking boots and hike on trails that are within your abilities. During the winter, trails can be covered in snow and ice, or be muddy. Foot traction devices and walking sticks are recommended. There are boot washing stations at the new Sunset Point restroom facility. People do not realize that Bryce Canyon is above 8,000 feet in elevation and arid. For these reasons, visitors may want to dress in layers and take plenty of water with them. Remember, erosion is constant so be aware of your surroundings.