Before abruptly reversing itself, the trail makes a long swing northward. Leaving the pines, it crosses the maroon sediments that give the Red Beds Trail its name. The exposed formation has been cut into steep cliffs by the river. Deposited some 180 million years ago during the Jurassic Period, when the land surface was low and adjacent to a sea, this mixture of siltstone and sandstone is poorly cemented together. As a result, it weathers easily, forming a striking, ravine-cut outcrop wherever the stratum is exposed. Few plants colonize this handsome formation, making it stand out against the dull, igneous-gray Tower and its dark wreath of ponderosa.
As the sun approaches zenith, I am nearing the end of the trail circuit. Coming back closer to the Tower, the trail re-enters the pine forest. I welcome the perceptibly cooler air and dimmer surroundings beneath these big, yellow-barked trees. Here, where lichen and moss cap boulders and fallen logs, is a good spot for lunch. I sit with my back to the trunk of an ancient, fallen giant whose length has collapsed and defines the contours of the ground. Its exposed, rotten heartwood nourishes miniature fungi-gardens.
Compared to the sharp shadows and glare of the meadows and thickets I have left behind, the evenly shaded pine forest seems serene. Except for a diminutive red-breasted nuthatch that patrols up and down a nearby tree trunk, gleaning grubs and other insects as it goes, there is no perceptible motion. Even the few shafts of sunlight that touch the forest floor here seem, like me, to be intruders. Sound itself seems unwelcome. No birds sing or squabble or dart their colors to catch the eye. If anything walks or hops about, no leaves rustle to reveal its presence. Years of needle-cast shroud the uneven ground, giving the dissimilar shapes of rock and downed trees a sameness of color and texture.
Comparatively few life-forms inhabit the pine forest. Fewer kinds of plants grow beneath the pines than grow in the deciduous woodland. And fewer plant types mean a more limited diet for herbivores such as insects, mice, cottontails, and deer. The scarcity of insects also reduces the number of bird species that will find the habitat attractive.
The relative absence of life on the forest floor begins in the soil. Pines create acid soil conditions which do not promote bacterial growth. Decay, therefore, carried on primarily by fungi, takes place very slowly. The result is the thick accumulation of discarded needles and branches, the resinous, sweet-smelling “duff.”
Not far upslope from the trail a porcupine scuttles toward a stand of young pines. It moves slowly and silently, its quills making it look prehistoric. Again I am struck by the apparent changelessness of the pine forest.
But looking around, I find everywhere signs that indicate change and struggle. At the bases of the giant pines—some of which may be more than 200 years old—are fire scars. Most of the mature trees survived the frequent fires that once raced through here. Their bark was thick and fire-resistant, and they had few lower branches to pass the flames up into the vulnerable upper branches. But that was before the white man interrupted the long reign of wildfire. Ironically, fire had actually helped to maintain the health of the forest. Grass fires, sweeping into the pines, burned off the accumulations of litter and killed many of the crowded younger trees. Tinder was thus removed before it could build to dangerous levels.
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A Home for Wildlife
Some animals indigenous to the Great Plains find a protected home in Devils Tower National Monument. Gone from this area are the bison that once roamed the prairie grasslands in great numbers, and the fastest plains animal, the pronghorn antelope, is rare. The most noticeable mammals here are the whitetail deer and the prairie dog (See pages [48]-65 for pictures and text about the prairie dog and its predators), but with careful observation you can spot some of the smaller animals that inhabit the grasslands, woodlands, and rocky areas around the Tower.
The raccoon, primarily a nocturnal creature, prefers woody or swampy areas and often dens in hollow trees.
The porcupine, which has up to 30,000 quills, dwells in the forest and often is seen in the tops of trees.
The longtail weasel usually lives in deserted burrows and preys on small mammals, some birds, and other animals.
The rare swift fox sometimes enlarges and inhabits an old prairie dog burrow. The red fox is more common here.
The pocket gopher is a remarkable burrower, creating up to 150 meters (500 feet) of tunnels close to the surface.
The thirteen-lined ground squirrel lives in a burrow in open areas, feeding mostly on seeds.
Whitetail deer mostly inhabit wooded areas in the park, though you may see them in clearings. Often they wander into the campground near the Belle Fourche River at dawn and dusk, providing an added treat to those who spend a night or two in the park. Deer usually do not go beyond an area of 4 square kilometers (1.5 square miles) even when their food sources are limited. They are browsers, eating all foliage they can reach standing on their hind legs. So, you may notice most foliage denuded to a 1-meter (3-foot) level, especially where their populations are high.
Whitetail deer can run 56 kilometers (35 miles) per hour, jump 2.7 meters (8.5 feet) high, and leap about 9 meters (30 feet), all quite gracefully.