Chiricahua National Monument

July 22, 2004

Pc270111

Provided by: Andrew Sosis
Summary authors & editors: Andrew Sosis

The above photo was taken in late December (2003) at the Chiricahua National Monument in the Chiricahua Mountains of Arizona. Hiking here in the winter can be quite a surreal experience, combining desert flora and fauna with, on this day, a six inch (10 cm) snow cover. Due to differences in shading and exposure, you would be walking through rather deep snow on the northern side of a ridge, and then upon turning the corner, there would be little or no snow on the southern side. The geologic formations found in Chiricahua National Monument result largely from a volcanic eruption that occurred approximately 27 million years ago. The force of this immense eruption was estimated to be 1,000 times greater than the 1980 eruption of Mount St. Helens. More than 2,000 ft (610 m) of highly silicious ash and pumice was deposited during this eruptive event. Eventually, this mixture fused into a rock known as rhyolitic tuff, and over the eons, the tuff eroded into spires and unusual rock formations familiar to visitors today.

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