On the Way to Roden Crater
Among the Mounds and Craters of Northern Arizona

2850 Roden Crater, James Turrell's unfinished earthwork, is one of many craters in the area modified by the hands of man. CLUI photo

JAMES TURRELL'S RODEN Crater is perhaps the most elaborate, anticipated, and delayed land art project in the nation. While it remains a perpetual construction site for the foreseeable future, and closed to the public, it is not the only transformed crater in the neighborhood. This remarkable region, known as the San Francisco Volcanic Field, is peppered with hundreds of cinder cones and lava flows, with landscapes that range from the supremely trammeled, to the utterly impassable. There are dozens of curiously altered landforms here, potential perceptual and interpretive attractions, at a crater-themed landscape discovery park, free and open to the public, for the most part.

This is a chaotic land of dirt roads, sand traps, dead-ends, ranches, and right-angle turns, due to abrupt topographic shifts, loose drainage channels, and irregular land ownership, a mix of federal, private, and state lands, in the common checkerboard arrangement of alternating square mile township and range sections. On the east side the border is abrupt, at the canyons of the Little Colorado River, and the Navajo Nation, another place altogether. Out of bounds.

2851 Sheep Hill is one a few cinder cones in the volcanic field that has been deconstructed to form a sculptural monument to construction. At its base, its constituents are sorted in bins, arranged by color and texture, like unmixed paints on a palette, extracted from a painting in reverse. CLUI photo
There are just a few paved roads into the area. The main one is Highway 89, heading east then north out of Flagstaff. On the northeast side of town is Sheep Hill, one of several cinder cones in the area that are dug up commercially for the textured rock. Cinder Haul Road curves up the hill, much of which is now gone, spread around elsewhere in the state. At the base of the hill are some of the provisioners of this mountain:  AZ Materials Inc., and the Landscape Connection, Inc., Materials and Yard Décor. A few miles east in Winona, the Darling Pit has similarly eaten up much of Cinder Mountain. North a few miles are some pits west of Robinson Crater. Confusingly, around here mounds can be craters, and craters can be mounds, some naturally formed, some created by man’s hand.

2868 Cinder Lake Landfill Mound. CLUI photo
Continuing out of town, as Highway 89 curves north, is Old Caves Crater.  If you take a right after the mound, you will be on Cinder Lake Landfill Road, headed to Cinder Lake Landfill, a contemporary mound of effluvia and ejecta constructed by local residents–this is the main landfill for the city of Flagstaff. Just north of the landfill is Cinder Lake, a flat pan of black ash, where people drive dirt bikes in circles and spirals in an officially sanctioned Off-Highway Vehicle Area. It is a remarkably granular and soft surface, like a giant bowl of rough gravelly marbles. A few isolated full-grown pine trees poke up from the otherwise denuded black waterless lake of coarse pebbles.

2852 One of the remaining craters at Cinder Lake that were formed through a choreographed explosion to construct a model of the moon's Sea of Tranquility. CLUI photo

2869 The lunar craters of Cinder Lake are more discernible today from above. CLUI photo
In the 1960s, Flagstaff’s Astrogeology branch of the USGS created a version of the lunar surface here to train astronauts. A duplicate of the lunar craters found in the Sea of Tranquility (the proposed landing site for the first Apollo mission) was created here using buried explosives precisely scaled to form the right sized craters, and sequenced so that the ejected debris would fall in the correct layered order over one another. Over the course of a decade, future astronauts trained here, often fully suited, learning to use the tools for observation and sampling that were to be employed on the real lunar surface. The lunar rover drove all over this surface before going to the moon, making this possibly the only extra-terrestrial OHV area in the country open to the public.

To see a film about the project go here: astrogeology.usgs.gov/rpif/videos/making-craters


2853 Sunset Crater, spared from an explosion for a film production, is now an off-limits park. Though there is a visitor center and a walking trail at its base, nobody is allowed to climb the crater anymore. CLUI photo
Further up Highway 89 is the Sunset Crater, the youngest crater in the region, formed in a series of eruptions, some less than a thousand years ago. It's form and formation is typical of many of the older cinder cones here. During the eruptions, most of the magma came out explosively as ash and rock scoria, which blanketed the region. This ejecta was emitted sporadically, over days, weeks, and months, often as a fountainous cloud of liquid rock and gas, at 2,200 degrees, cooling and solidfiying before it hit the ground. It piled up, making a mound of cinder whose sides rest at the angle of repose, 33 degrees. Gases emitted during the eruptions chemically reacted with the black basalt, forming iron oxides, giving many of the mounds a reddish hue. Additional colors on these rubbley slopes are lichens, the early colonizers of this new land.

Sunset Crater became a National Monument in 1930, and is managed by the National Park Service. This came about after a plan to dynamite the side of the crater, in 1928, led to federal intervention to protect it. The proposed detonation was to create an avalanche for a Hollywood western film, Avalanche, based on a Zane Gray novel. (The Hollywood dynamiters were more successful in Cameron, Arizona, where they used a few too many explosives, and ended up showering rocks on the crew, and killing one spectator).

Since 1973, visitors have been forbidden to climb Sunset Crater, as the loose cinders of the slopes were being damaged by foot traffic. Instead, a walking trail was constructed at its base. After a few hundred yards of pavement, the trail enters the Bonito Lava Flow. A quarter or so of the magma that came out of Sunset Crater flowed, rather than spewed, creating this flowscape of lava. Beneath the surface crusts are layers of scabby flow formations as much as 100 feet deep, where hollow lava tubes have ice that lasts throughout the year.

2873 The Bonito Lava Flow, one of the least walkable landscapes anywhere. CLUI photo
This is one of the most jagged terrains imaginable–brittle, lightweight piles of crusting convolutions, that break, scatter, and clink. It is nearly impossible to walk through it if not for this constructed trail. The trail leads to a lava tube that partially collapsed recently and is now closed to the public.

2870 Wupatki National Monument. CLUI photo

The Park Service also manages the Wupatki National Monument, several miles away. There, the ruins of some old Indian pueblos, left from settlements that date back more than a thousand years, serve as a reminder that people were here to witness the dramatic eruptions that created Sunset Crater. It must have been quite a show.

2855 Line of sight tubes on the overlook promontory at Meteor Crater. CLUI photo
Though it lies 15 miles outside of the San Francisco Volcanic Field, one cannot exclude Meteor Crater from a discussion of the craterscape of northern Arizona. An anomalous coincidence of craterness, Meteor Crater was not formed by eruptions, but by the explosive impact of a 200-foot long meteorite 49,000 years ago. It is possibly the largest, most distinct meteor crater in the world, 4,150 feet wide, circular, with a raised rim of ejected material around it. Like Cinder Lake, the well-preserved crater was used as a training site for the Apollo program. Though unlike Cinder Lake you cannot drive around in it.

The visitor experience at Meteor Crater, which has been operated as a popular and privately owned tourist attraction for many decades, is robust. There are overlooks on the edge of the crater with line of site tubes, a crater-rim trail, a museum with displays about astrogeology, a stand at ground zero room, an introductory film, and windows framing views outward, like paintings in a picture frame.


2871 The Ground Zero Room. CLUI photo

2872 Picture windows at Meteor Crater. CLUI photo
With such a variety of possible perceptual experiences, Meteor Crater is currently the most complex and sophisticated perceptual crater experience among the many in the craterscape of northern Arizona. It’s like a populist version of Roden Crater, only 30 miles away. And, it’s open.

2875 Crater, museum? Sometimes they are two sides of the same coin. CLUI photo