Twenty seven million years ago a volcanic eruption of immense proportions shook the land around Chiricahua National Monument. One thousand times greater than the 1980 eruption of Mount St. Helens, the Turkey Creek Caldera eruption eventually laid down two thousand feet of highly silicious ash and pumice. This mixture fused into a rock called rhyolitic tuff and eventually eroded into the spires and unusual rock formations of today. The monument is a mecca for hikers and birders. At the intersection of the Chihuahuan and Sonoran deserts, and the southern Rocky Mountains and northern Sierra Madre in Mexico, Chiricahua plants and animals represent one of the premier areas for biological diversity in the northern hemisphere.