Saguaro National Park is an American national park located in Pima County in southeastern Arizona. 

The 92,000-acre park consists of two separate areas

the Tucson Mountain District about 10 miles west of the city of Tucson and the Rincon Mountain District 

which is part of the Sonoran Desert.  The landscape preserves fauna and flora, including giant saguaro cactus.

The surface igneous rocks of the Tucson Mountain District are very different from the surface rocks of the Rincon Mountain District

 During the past 30 million years, displaced rocks from beneath the Tucson Mountains

 Tucson Mountains District formed the Rincon Mountains in the Rincon Mountains District.  

Elevated, domed, and eroded, the Rincon Mountains are significantly higher and wetter than the Tucson Mountains. 

As one of the Madrian Sky Islands between the southern Rocky Mountains and the Sierra Madre Oriental in Mexico, 

Rincón supports high biodiversity and is home to many plants and animals that do not live in the Tucson Mountain District.