Sunset Crater Volcano National Monument

The third national monument we visited on Wednesday was located about 20 miles north of Flagstaff: the Sunset Crater Volcano National Monument. It is located within the San Francisco Volcanic Field on the Colorado Plateau that was active beginning six million years ago. Sunset Crater is the most recent eruption, exploding between 1040 and 1100. The Sinagua lived and farmed the area and so were witnesses to this eruption.

Sunset Crater is a cinder cone, forming when molten rock sprayed high into the air from a crack in the ground. The lava solidified and fell to Earth as large bombs or small cinders. Eruption after eruption occurred in this manner, building a debris pile up to 1,000 feet high. Two lava flows erupted near the vent, the Kana-a and the Bonito, and destroyed everything in their path. The entire event may have lasted 6 months to a year with a final eruption spewing red and yellow cinders out from the vent and onto the rim. The colorful glow from these cinders reminded people of a sunset and led to the volcano's name. The elevation at the summit is 8,029 feet with it's diameter at its base 1 mile. Approximately one billion tons of material was extruded from the vent.

We walked along a trail over the Bonito lava flow to the base of Sunset Crater. The gravel beneath our feet was black and the rocks a chunky, clinky form of lava called "aa." It is the same kind of lava flow that I walked over when on the big island of Hawaii. The rock is also known as "basalt."

The ancestors of today's Hopi people, the Sinagua, witnessed the eruption. In some Hopi accounts, the Qa'na Katsina caused Sunset Crater to erupt after people engaged in a life out of balance. The eruption is a living reminder that if people stray from their religious ideals and life, there may be another eruption.