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12. Chiricahua National Monument
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Southeast Arizona's Chiricahua National Monument provides evidence of the raw force of volcanic activity and the patient artistic ability of erosion. Often referred to as a "Wonderland of Rocks," this breathtaking scene sprang from a catastrophic volcanic explosion some 27 million years ago. One of the most large-scale eruptions in American Southwest geological history, this one covered an area roughly 1,200 square miles with a thick covering of pumice and ashes.
Chiricahua's unique terrain was produced from the Turkey Creek Caldera, a large volcanic crater north of the current monument. An large amount of pumice and ash was thrown by this eruption, which over time settled and compressed to create a rock type called rhyolitic tuff. In some areas reaching depths of up to 2,000 feet, this tuff layer became the canvas upon which nature would create her masterwork over millions of years.
A complicated interaction of several elements shapes the erosion process that turned this homogeneous layer of volcanic tuff into the strange scene we observe now. The main sculptor has been water—rain and snow in particular. Water slowly widens these gaps in the rock as it seeps into cracks and crevices using a mix of physical and chemical degradation. Freeze-thaw cycles hasten this process even more since water expands when it freezes, stressing the nearby rock and breaking and separating it.
Furthermore quite important in forming the Chiricahua scenery is wind. It contains abrasive particles that gradually erode the rock surfaces, helping to create the unique qualities of the location. Towering spires, balanced rocks, and the park's well-known "hoodoos"—tall, thin spires of rock rising dramatically from the ground—have been produced by the differential erosion of the volcanic tuff, whereby softer areas erode more rapidly than harder ones.
Among the most recognizable elements of Chiricahua National Monument are the many balanced rocks. Under a tougher capstone, erosion wears away softer rock, producing these precarious-looking formations that seem to be a boulder softly perched atop a little pedestal. Although they seem unstable, many of these balanced rocks have been in place for thousands of years, evidence of the slow rate of geological change under desert conditions.
President Calvin Coolidge named the monument in 1924 to protect these unusual geological formations. But its importance transcends geology as well. The area boasts a rich cultural legacy having housed several Native American tribes, including the Chiricahua Apache, for whom the monument is named. During their fights with European immigrants in the 19th century, the Apache made use of the natural defenses the tough terrain offered.
Chiricahua National Monument is rather unknown among other national parks and monuments in the Southwest despite its amazing beauty and geological importance. With only over 60,000 tourists annually, its far-off position in southeast Arizona, some 120 miles southeast of Tucson, helps to explain its reduced visitor count. This relative remoteness has helped to maintain the landscape's unspoiled beauty and gives guests, in more crowded parks, a sense of serenity and closeness to nature that can be difficult to obtain.
The monument has a range of hiking paths that let guests close-up view its distinctive geological characteristics. For those unable of hiking, the eight-mile Bonita Canyon Drive offers access to scenic views that highlight the dramatic landscapes of the monument. The Heart of Rocks Loop, for example, transports hikers through a wonderland of oddly shaped rock formations including well-known features like "Duck on a Rock" and "Thor's Hammer."
Geologically speaking, Chiricahua National Monument is a valuable location providing information on volcanic processes, erosion trends, and long-term landscape change in arid surroundings. It also is very important in maintaining the special environment of the "sky islands," isolated mountain ranges in southeast Arizona with a wide variety of plant and animal life.
Places like Chiricahua National Monument become increasingly important as climate change keeps affecting the American Southwest. They provide natural venues for researching how variations in temperature and precipitation pattern affect dry environments and ecosystems. The preservation of this special geological and biological treasure guarantees that other generations will be able to wonder at the beauty of the planet and acquire understanding of its dynamic geological processes.
