* Astronomy

Reaching 12,633, Mount Humphreys gains less than half the altitude of the worlds highest peaks, but it offers a compelling story on the long, complex relationship between human beings and mountains with its most recent outpouring in 1064-65, which had a dramatic effect on existing civilisations and left the raw, colourful landscape of Sunset Crater National Monument.
Geologists have counted some 600 different volcanoes in a field of peaks, flows and cinder cones that covers much of north-central Arizona, from the Little Colorado River west to Ash Fork and from Cameron down to the 1,000-foot-high line of the Mogollon Rim, which is the southern edge of the Colorado Plateau. Geologists have laboriously dated the layers of lava and concluded the major eruptions took place every 7,000 to 13,000 years.

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