Hunting for Sinkholes on the Walhalla Plateau, northern Arizona
The rocks exposed on the Walhalla Plateau of northern Arizona include the Harrisburg Member and Fossil Mountain Member of the Permian Kaibab Formation. The Kaibab is a fossiliferous, limestone riddled with karst features. In northern Arizona’s breccia pipe zone, karst sinkholes can mask economic breccia pipes enriched in uranium, copper and other minerals.
George Billingsley, Philip Stoffer and Susan Priest (USGS), ’Geologic Map of the Tuba City 30’x60’ Quadrangle, Coconino County, Northern Arizona’ (2021) identifies a number of sinkholes nestled in the ponderosa pine forest of the Walhalla Plateau. LiDAR data from OpenTopography (image on the right) suggests there may be additional sinkholes not shown by Billingsley and others (2012). This may be due in part to the map scale, which is not conducive with showing smaller geologic features.
Compare the two figures for sinkholes, which are symbolized as triangles on the geologic map. (Map scale differs greatly, so the maps include orientation points 1 and 2 to assist with comparison.) On the LiDAR image, I’ve used orange arrows to point to what appear to be prominent sinkholes. I can’t rule out some may be cattle tanks. Not all potential sinkholes are marked by orange arrows.
- Billingsley and others (2012), Geologic Map of the Tuba City 30' x 60' quadrangle, Coconino County, Northern Arizona. U.S. Geological Survey Scientific Investigations Map 3227.
- OpenTopography LiDAR data can be found at https://opentopography.org/
- Wenrich, K.J. and Sutphin, H.B., 1988, Recognition of Breccia Pipes in Northern Arizona, 1988, Fieldnotes V18, No 1.
- Spencer J.E., Wenrich, K. and Cole, T., 2015, Partial database for breccia pipes and collapse features on the Colorado Plateau, northwestern Arizona. Arizona Geological Survey Digital Information, DI-42, 5 p., 1 map plate, shapefiles, and Excel Workbook