An exposure of a severely weathered and altered mafic dike (left) adjacent to gneiss (right) exposed on the lower Catalina Highway. Photo by Esty Pape, Geologic explanation by Jon Spencer.
Online resources:
Bezy, J.V., 2016, A Guide to the Geology of the Santa Catalina Mountains, Arizona: The Geology and Life Zones of a Madrean Sky Island. Arizona Geological Survey Down-to-Earth # 22, 83 p. https://library.azgs.arizona.edu/item/DTES-1552428346471-69
Spencer, J.E., 2006, A geologist's guide to the core complex geology along the Catalina Highway, Tucson Area, Arizona. Arizona Geological Survey Open File Report, OFR-06-01, 38 p. https://library.azgs.arizona.edu/item/AOFR-1552429673312-319
Bezy, J.V., 2004, A Guide to the Geology of Sabino Canyon and the Catalina Highway. Arizona Geological Survey Down to Earth, DTE #17, 56 p. https://library.azgs.arizona.edu/item/DTES-1552427811183-395
Photographer: Esty Pape
Photo Date: September 2018