The mountains around Sabino Canyon were formed by multiple forces, including volcanic activity approximately 70 million years ago (mya), intrusion of molten magma 30 mya, and Basin and Range faulting 10 mya. The banded rock found in Sabino Canyon, called gneiss, was formed underground when younger Wilderness granite (white) intruded into the older layers of Oracle granite (dark) during the formation of the Catalina Mountain range.
The geology table has samples of the 5 minerals (feldspar, quartz, mica, garnet, and magnetite) that make up gneiss. There is also a map of Arizona at the table that shows the three regions that make up Arizona (Colorado Plateau, Transition zone and Basin and Range) with rock and mineral specimens denoted where they were found on the map.
Meet at the ramada in the plaza outside the Visitor Center.