View from turnout along the Catalina Highway which goes up to the top of Mt. Lemmon to the East of Tucson. The view faces West over Tucson and lower levels of the Santa Catalina mountains composed at this point by lifted and upturned mixed granite and gneiss from Proterozoic to Cenozoic Eons.
Another view along the Catalina Highway showing weathered granite in the foreground and uplifted, tilted and weathered strata in the distance.
Overlook along the Catalina Highway with weathered arrays of metamorphosed granite in the foreground.
At a low elevation stop along the Catalina Highway looking uphill at granite and Saguaro cacti.
Granite rock with quartz pegmatite in a barrier curb along the Catalina Highway 
Metamorphosed granite with lighter quartz. Much of the granite comes from Cenozoic sills injected into older rock 45 million years ago and then subjected to heat and pressure associated with folding and uplift and then exposed by erosion..
Quartz and muscovite (mica) in metamorphosed granite.
Mylonitic striations in metamorphosed granite.
Saquaro cacti and Tuscon Mountains in Saquaro National Park
Saquaro cacti and Tuscon Mountains in Saquaro National Park
Volcanic tuff from eruptions 70 Ma form the bulk of the Tucson mountains covered by cacti and other flora in Saguaro National Park.
I visited the Arizona-Sonora Desert Museum which has an outstanding walking exhibits of flora/fauna of the Sonoran Desert. Carry Water!