Formed more than 25 million years ago, the rocks are an interesting example of Catalina Gneiss, in which sheets of other minerals were melted into one another while deep underground.
Here’s a brief video showing Javelina Rocks:
The oft-photographed rocks also mark the trailhead for the Tanque Verde Ridge Trail, a 6.9-mile one-way route that offers some excellent views of the Tucson basin.
Learn more about national park day hiking trails in my Best Sights to See at America’s National Parks guidebook.
