About 60 million years ago, in early Tertiary times, a mass of molten magma forced its way upward through the relatively level layers of red, yellow, green, and gray Jurassic sedimentary rocks that make up northeastern Wyoming. The mass cooled into a hard, igneous rock called phonolite porphyry. An earlier flow of magma occurred about 6.5 kilometers (4 miles) to the northwest.
As millions of years went by, the soft sedimentary rocks were eroded, exposing what eventually became known as Devils Tower and the Little Missouri Buttes. The erosion process continued, baring more and more of the dense, gray rock. Apparently, as the magma cooled, the rock contracted and fractured into columns of 4, 5, 6, or more sides. The larger columns are 2.5 meters (8 feet) in diameter at their base and taper to about 1.2 meters (4 feet) at the top.
Today the Tower rises 264 meters (867 feet) from its base to an elevation of 1,560 meters (5,117 feet). The top is 386 meters (1,267 feet) above the Belle Fourche River at the entrance road. The tear-drop shaped top measures 91 meters (300 feet) from north to south and 55 meters (180 feet) from west to east. The sides rise almost vertically from the base for 12 to 30 meters (40 to 100 feet) to a narrow bench, from which they again rise steeply to the summit.
A thwack of an ax against wood puts an end to my daydreaming. My companion the cottontail hops for cover. The pair of magpies that have been feeding on the remains of a road-killed ground squirrel flash upward to safety. The gradual awakening of campground life inspires woodpeckers to hammer in the cottonwoods, and a yellow-breasted chat adds its odd jibber to the collected noise.
Gathering up knapsack and camera. I start my hike to the Tower. Already the sash of river fog has lifted and the air warmed to shirtsleeve comfort. From somewhere on the red cliffs that gown the Tower’s base, the faint singing of a rock wren beckons. Ahead lie 13 kilometers (8 miles) of trail, looping through a mosaic of sights, sounds, and smells of grassland, pine forest, woodland, and river.
From Dog Town to Ant Colony
Leaving the campground, I follow the trail that leads through the prairie dog town. The prairie dogs stand upright as I approach. The ones nearest the path begin their warning call, a monotonous “churk-churk-churk-churk.” The closer an intruder comes, the lower the animals sink into their holes, and the faster and shriller the chant becomes. Finally, with a last flick of its nervously twitching tail, each disappears into the safety of its burrow.
Prairie dogs, like the bison that once shared their vast range, are now reduced to remnant populations. Two hundred years ago, there were billions of prairie dogs on the shortgrass plains; these large ground squirrels had successfully adapted themselves to the harsh conditions. Perfect digging machines, they escape most predators and the extremes of the weather by spending more than half their lives underground.
The prairie dogs near the road do not even bother to sound a warning as I approach. They seem to be different creatures from the wild, suspicious animals farther from the road. Laconic and fat from handouts, more curious than cautious, they approach rather than retreat. These animals are easier targets for the redtail hawk that is screaming above the river timber, or the golden eagle that sails high overhead.
Across the road, the trail leaves the grassland of the prairie dogs and climbs steeply among ponderosa pines. Already the sun grows hot. At the edge of the forest, I stop to rest and survey the landscape before me. Spread out below, and now shimmering with sundance heat, the buff-colored dog town stands out in stark contrast with its darker, greener surroundings.
Although I sit only 30 meters (100 feet) or so above the dog town, I am struck by what my vantage point reveals: a clear patchwork of life communities. The loop of the Belle Fourche and the June-bright leaves of the deciduous trees lining its course provide a bright counterpart to the somber, pine-scattered ridge beyond. Just a short distance away the ponderosas appear more black than green. It was just such a quality that gave the distant, pine-covered mountain range to the east the name Black Hills.
From where I sit, the lobe of the level bench of land that juts into the river looks as if it were graded and maintained by man, for its close-cropped vegetation contrasts greatly with the rugged ridge beyond. But this old floodplain was graded level by the river, and prairie dogs, not machines, clip the vegetation.