by Rob Samuelsen
Geologists estimate that Arizona has had five volcanic periods ultimately resulting in three active volcanic fields today. The San Francisco volcanic field (aka Flagstaff area) includes more than 600 volcanos and the most recent eruption – Sunset Crater – occurred about 1,000 years ago. Today, it’s a dormant but not extinct volcano priming itself for its next millennial eruption.
Buried in the 1065 eruption are settlements of the Sinagua culture. Nearby ruins suggest that they moved to nearby Wupatki and Walnut Canyon. As possible descendants of the Anasazi and predecessors to the Hopi and Zuni, memories of the eruptions are embedded in Hopi and Zuni lore, ceremonies, and traditions.
Volcanic eruptions rarely come without warning. Today’s science measures pressure, earth movements, and chemistry to determine and predict activity. What can’t be predicted with preciseness is the exact moment of eruption, the related vents, viscosity of the lava, noxious gases, or strength of the blast. Nor can we predict the direction of the flows or winds. When 2,000 F degrees of melted rock is heading your way, it’s best to do as the Sinagua people did – get out of the way!
It’s hard to imagine rock that hot. Perhaps the best man-made example is seen in the slag piles from smelting operations. Slag, a glass-like by-product of smelting, flows and hardens in a similar fashion to lava. Some flows are smooth like glass and others are chaotic like a storm-tossed sea. Embedded within a lava flow can be all sorts of freakish formations including domes, dikes, dams, and lava tube caves, hardened conduits of low viscosity lava. Similarly, depending on the mineral content, lava can be different hues, even the color of a sunset as exemplified by John Wesley Powell’s naming of the peak.
Volcanic terrain is an eerie mix of anticipation and awe. The black sheets and folds of rock remind me of an unmade bed awaiting the explosion of a roman candle on steroids. It’s a subtle feeling, but as I hike through fields of basaltic rock, I can’t help but think about escape routes in case of renewed activity. Intellectually, I know I’d be warned, but emotionally, I’m worried. Walking on cinders is much like walking on sand dunes. For each step forward, it’s a half a step backward. A few years ago, I climbed the 800-foot SP Crater (about 15 miles northwest of Sunset Crater) but it felt like climbing 1,600 feet. It’s a better workout than a stair-stepping machine! The aggregate is coarse and outcroppings can be sharp and abrasive. Hiking off trail left me bloodied from scrapes, scratches, and chafes.
At Sunset Crater National Monument, there are a number of groomed and informative trails. Many years ago, I climbed Sunset Crater, but the National Park Service has since closed the trail to the rim because of erosion issues. Instead, there are several easy interpretative trails and a tougher summit climb up nearby Lenox Crater. It is a beautiful landscape of colors, shapes, and intrigue.
