Thursday, December 22, 2016

Trails head over half-billion-year-old rocks

The largest outcropping at Javelina Rocks.
Day hikers can scramble over boulders more than a half-billion years old at Javelina Rocks in Arizona’s Saguaro National Park.

There’s no official trail
at the rock formation,
but several narrow paths circle and head into the five rock outcroppings. You easily can put on a half-mile of walking at
the sight in the park’s eastern Rincon Mountain District.

To reach the trailhead, from Interstate 10 in Tucson exit onto East Speedway Boulevard and head east. Turn right/south onto Freeman Road then left/south onto Old Spanish Road. Next, enter the park by turning left/east onto Cactus Forest Drive. The park’s eight-mile road eventually becomes a one-way. A parking pullout for Javelina Rocks is between the six and seven mile markers. Expect the lot to be full on spring weekends.

The trail heads northwest from the parking lot toward the largest of the five outcroppings. Saguaros, cholla cacti, and desert wildflowers surround the rocks.

The outcroppings are Santa Catalina gneiss, formed some 541 million years ago when a tectonic plate begin to split apart. As it did, land heading in one direction slipped downward at an angle against the land moving in the other direction, This friction resulted in high temperatures and pressures that created the gneiss.

Five minerals – quartz, feldspar, mica, magnetite, and garnet – make up the gneiss. They are quite resistant to erosion, which has exposed the outcroppings by blowing and washing away the weaker soil surrounding them.

The three smaller outcroppings are perfect for kids to scramble upon and make a great spot to watch sunsets. The larger two outcroppings offer a great challenge to those who wish to test their scrambling skills, and because of that you’ll also enjoy more solitude there.

The trails between them offer great views of the Catalina Mountains to the north. During winter, they’re typically snow-capped.

If lucky, you may spot the rock’s namesake, the javelina. The pig-like creatures like to congregate at the rocks, which provide shade and shelter.

Other small animals can be found at the rocks as well. There will be plenty of small, harmless lizards, and sometimes a curve-billed thrasher can be spotted perched on the ocotillo.

Be sure to bring some lunch or a snack with you. After clambering around the rocks, drive to the nearby Javelina Picnic Area, where the outcroppings make a great backdrop to a meal.

AERIAL MAP OF SITE
Click for larger version.