Hueco Tanks Professional Review and Guide
"About 35 miles east of El Paso. An easy day hike through the jumbled rock masses of Hueco Tanks. Special Attractions: Rock climbing, pictographs. Permit required for camping. Three large masses of rock form what is known as Hueco Tanks. The igneous rock, a syenite porphyry, intruded into layers of older sedimentary rock. Over time, the limestone eroded away, leaving piles of rock 300 feet high as islands in the desert. The park's name comes from the Spanish word for hollow, referring to the depressions, often water-filled, in the rock.
The park lies in dry Chihuahuan Desert and receives only about eight inches of rain per year. However, the runoff from the bare rock concentrates in hollows, canyons, and cracks in the rocky islands. The coarse igneous soil in these places holds the moisture, allowing trees such as the Arizona oak and the one-seed juniper to grow in the dry climate. Man first visited Hueco Tanks as far back as 10,000 years ago."