The Santa Catalina Mountains are north of Tucson and are the most prominent mountains of Tucson’s five ranges. The highest point in the Santa Catalinas is Mount Lemmon, with an elevation of 9,157 feet. Surprisingly, Mount Lemmon receives annual precipitation of 180 inches. Pretty impressive for an arid environment! The Santa Catalinas is bordered by normal faults, which are steep sloping cracks in Earth’s crust. The ground to the west of the fault slipped downward, and the east side thrust upward, exposing the rugged granites that make up the Santa Catalinas. These granites formed miles below the Earth’s surface when magma solidified over millions of years, giving the mountains their rugged and foreboding features. Fortunately for Tucson, there’s been no movement along this fault for five million years. One of the Tuar Tums underground caverns is located in the Santa Catalinas. It’s also where Asa and Alexa escaped through the port door to begin her training.