A Day at Devils Tower
Pouring a mug of boiled coffee, I wait for the sun to make its appearance. The cup steams in the damp, cool morning air. Shivering, I press both hands to the heat the thick porcelain holds.
The sky begins to purple, and stars dim perceptibly. Through the campground cottonwoods, the immense, shadow-black bulk of the Tower materializes against the sky. It is possible now to discern the flight of bats overhead. But, in an instant, their swirling, night-long ballet vanishes with the darkness.
From my campsite along the Belle Fourche—this narrow, meandering river the French fur trappers named “the beautiful branch”—I listen to the first sounds of the day. Across the river a great horned owl protests the morning’s swift advance. Coming through the veil of river fog, its haunting, pervasive hoo-hoo-hoooo is enough to freeze the blood of cottontails.
Even before the first hint of light, robins had begun to sing softly. In these unhurried morning songs they prove themselves thrushes. With the increasing light, the growing blend of wren, vireo, and thrasher music intensifies. These soft phrasings soon quicken into proclamations of territory, and meadowlarks, mourning doves, and yellowthroats compete across thicket, river, and meadow, their singing seemingly sharpened for distance and authority.
Nearby, a cottontail grazes on the dew-bent grass. It pauses occasionally, pointing its ears and working its nostrils in my direction. Three whitetail deer continue their cautious single-file approach, heading from the river bottom toward the higher ground of the prairie dog town. Crossing the campground, they repeatedly stop to inspect their surroundings. A log snaps and whistles in my fire, bringing their heads about in immediate, almost mechanical unison. Deliberately the lead animal lifts its tail to expose its white, silent signal of danger, and all three step smartly away as if in time to a fast metronome.
Direct sunlight spotlights the Tower. As though to challenge the sudden appearance of a gigantic, equally yellow competitor, a meadowlark takes wing, singing its loud, clear claim over the prairie dog town. Dawn is announced, the day begun.
The level rays of the sun accentuate the Tower’s vertical polygonal columns. The stark contrast of light and shadow imparted by the graceful taperings of the soaring, many-sided columns give the Tower a man-made look. In this light it resembles the ruin of a stupendous ancient temple, not the casual result of some remote geological event.
Sipping the strong coffee, I wonder at the long procession of vanished Indian societies that camped and hunted here periodically through the centuries. These ancient peoples devised various stories to explain such an unusual landmark. And yet what science now says about the creation of Devils Tower would have seemed to those tribes as fantastic as their legends of a gargantuan bear gouging the rock seem to us today. Minor uncertainties remain, but geologists have pieced together a rough picture of the Tower’s probable origin. Some 60 million years ago, great Earth stresses began to deform the crust of the continent, resulting in the uplifting of the Rocky Mountains and Great Plains region. As the surface rock layers began to crumple and fault, magma from deep inside the Earth welled up into many of the resulting gaps and fissures. In many places on the continent, spectacular volcanoes formed, erupting with explosive force.
As the Rockies were being created, the climate of the continent’s interior began to change. The long reign of the dinosaurs that had presided over a stable, tropical landscape was coming to an end. The climate was gradually becoming cooler and drier. Doubtless the immense volumes of volcanic ash ejected into the atmosphere prevented a percentage of solar heat from reaching the Earth. Certainly the rise of the Rocky Mountains to the west influenced the old weather patterns. As the mountain blocks rose higher, they intercepted the warm, moist winds that blew inland from the Pacific. With the air masses rising ever higher, more and more of the moisture that had watered the extensive inland Cretaceous forests and swamplands was prevented from reaching what we know today as the Great Plains.
Steadily the forests retreated eastward as the “rain shadow” cast by the mountains extended eastward, shutting off the moist, warm Pacific winds. No longer moderated by these winds, the mid-continent was increasingly opened to seasonal invasions of northern arctic air. Newer ecosystems, such as deserts and grasslands, slowly evolved to replace the lush forests and swamps that had for so long sustained the dinosaurs. Just as drought, fire, and temperature extremes began to alter the old order in the plant kingdom, so did the more adaptable mammals and birds begin to replace reptiles as dominant animal forms.
Both the Kiowa and Cheyenne Indians held similar legends on the origin of the Tower. The story goes that tribal members were surprised by a gigantic bear, and their incantations caused a low, flat rock to rise, lifting them above the reach of the bear. The massive beast then gouged huge vertical marks into the rock as it attempted to reach the people. Finally, the Indians were able to kill the bear.
But not all the magma that welled upward during this restless period reached the Earth’s surface. Extensive masses were trapped far below the surface, where they gradually cooled and congealed. The Missouri Buttes and Devils Tower, however, are believed to be necks of extinct volcanoes. Geologic evidence indicates the Missouri Buttes formed first in two separate eruptions. The magma hardened, plugging the plumbing underneath. A third eruption to the southeast resulted in Devils Tower.
During the ensuing tens of millions of years, the gradual erosion of the overlying rock strata revealed these intruded plugs of volcanic rock. Since this dense, hard igneous rock resists erosion much better than the surrounding sedimentary rock, these formations will continue to stand out as features.
That ancient land of sedimentary rock through which the molten mass of Devils Tower penetrated may at one time have been as high as the golden eagle I now see drifting high above the Tower. Circling slowly in its morning hunt, the eagle spirals upward on the currents of warm air rising off the sun-heated rock. Perhaps it now soars at the elevation of the land long ago when the heavy, ringing-hard rock of Devils Tower oozed like paste far below the surface.
Today the top of the Tower is 386 meters (1,267 feet) above the Belle Fourche River. If that warm, Cretaceous landscape rested 600 meters (2,000 feet) above the present summit of the Tower, then more than 900 vertical meters (3,000 feet) of sedimentary rock has been pared away in the last 60 million years.
The relentless physical agents of erosion—running water, wind, and frost action—together with chemical breakdown of rock particles, continue to alter the landform. Given enough time, even the very hard rock of the Tower itself will waste away.
Sixty million years ago, when dinosaurs Triceratops and Tyrannosaurus Rex duelled beside the lush river banks of the predecessor of the Belle Fourche, the ancestor of the golden eagle was flying overhead. Millions of years hence, a descendant of the eagle might soar above this same Wyoming landscape. Missing will be the unique shaft of fluted rock we call Devils Tower. And what of the men, who for a mere eyeblink of time, hunted in its shadow or came to wonder at its somber countenance in the morning sun?