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Field Division of Education
The Geology of Devils Tower National Monument
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The name now generally applied to this elevation is Devils Tower. Newton (1880) states that the name appearing on the earliest map of the region is, "Bear Lodge, (Mato Teepee)", and this is the name used in most of the earlier papers.

Jenney (1880) described the Little Missouri Buttes and Devils Tower as seen from the summit of Warren Peaks as follows: "To the west some twenty miles away, Bear Lodge Butte (Mato Teepee) and the Little Missouri Buttes appear in line. From this distance the former resembles in appearance the huge stump of a tree, its surface curiously striated vertically from top to base, and being perched on the crest of a high, flat topped ridge, it becomes a very prominent landmark, which once seen, is so singular and unique that it can never be forgotten. Although the Bear lodge country is an elevated region, and the different streams have a considerable fall before reaching the Belle Fourche, yet topography is quite peculiar in the prevalence of long, flat-topped ridges or mesas between the narrow and deep valleys and canyons of the creeks. This is due to the resistance to erosion offered by hard and continuous strata of sandstone of the Jurassic and Cretaceous formations, which are here almost horizontal in their bedding, with a gentle slope away from Warren Peaks."

Newton and Jenney state that "Bear Lodge" was not reached by the Warren expedition, but that while the Raynolds expedition was in the vicinity of the Little Missouri River two attempts, the last successful, were made by Mr. Hutton to reach it. Since he recorded no particular description of it, Newton and Jenney's examination in 1875, "had all the charm of novelty. Its remarkable structure, its symmetry and its prominence made it an unfailing object of wonder. It is a rectangular obelisk of trachyte with a columnar structure, giving it a vertically striated appearance and it rises 625 feet, almost perpendicular, from its base. Its summit is so entirely inaccessible that the energetic explorer, to whom the ascent of an ordinarily difficult crag is but a pleasant pastime, standing at its base could only look upward in despair of ever planting his feet on the top."

Russell (1896) also remarks on the inaccessible character of the summit. "The strongest and most experienced mountain climber must pause when he has scaled the rugged cliffs which form the immediate base of the tower and gains the point where the individual prisms make their abrupt curve and ascend perpendicularly. Beyond that point no man has ever reached, and it is safe to say, never will, unaided by appliances to assist him in climbing." Jaggar, (1901, footnote p. 255) states in regard to the ascent of Devils Tower that by 1901 such appliances had been recently used. "With the aid of iron bars driven into the angle between two sloping columns, a rude ladder was constructed and ascent to the summit was made;" a fact attested by a small flag, visible from below which was left on the highest point of the tower.

Russell (1896) in his work on the igneous intrusions of the Black Hills has given a vivid description of the tower. "When Mato Teepee is seen from almost any locality in the valley of the Belle Fourche within a radius of several miles, one is not only forcibly impressed by the grandeur of the monumental form that dominates the landscape, but is delighted by the brilliant and varied colors of the rocks forming the sides of the valley and the immediate base of the tower. The Red Beds in the lower portion of the river bluffs show many variations of pink and Indian red, and have been sculptured into architectural forms of great beauty. The less brilliant Jurassic sandstones resting upon them and forming the upper portions of the bluffs, serve to carry the eye from the rich colors below to the dark forest of pines that grow above and to the still more somber precipices of the great tower which always appears in bold relief against the sky."

Darton (1909) describes Devils Tower as one of the most conspicuous features of the Black Hills province. It is a steepsided shaft rising 600 feet above a rounded ridge of sedimentary rocks, which in turn lie 600 feet above the Belle Fourche. Its nearly flat top is elliptical in outline, with a north-south diameter of more than 100 feet and an east-west diameter of about 60 feet. Its sides are strongly fluted by the great columns of the igneous rock and are nearly perpendicular except near the top, where there is some rounding, and near the bottom, where there is considerable outward flare. The base merges into a talus of huge masses of broken columns lying on a platform of the lower buff sandstone of the Sundance formation. Lower down are slopes of Spearfish red beds, which present high cliffs to the east, on the bank of the Belle Fourche. All the strata lie nearly horizontal, with a slight downward deflection toward the center of the igneous mass. In the lower ridges northwest of the tower the strata are somewhat tilted, but apparently this is due to undermining by erosion on the adjacent gulches. The great columns of which the tower consists are mostly pentagonal in shape, but some are four or six sided. The average diameter is six feet, and in general the columns taper slightly toward the top. In places several columns unite in their upper portions to form a large fluted column. The columns are not perpendicular, but slope inward toward the top, the angle being 4° to 5° on the west side and 10° to 12° on the east side. They are not much jointed but are marked horizontally by faint ridges or swellings, which give the rock some appearance of bedding, especially toward the top of the tower. Near the top the rock is much jointed and irregularly fissured, and is more or less decomposed, crumbling into rounded fragments. The color at the top is brownish, mottled with dirty yellow-green, due to lichens. In the lower quarter or third of the tower, the columns bend outward and merge rapidly into massive rock, which toward the base, shows but little trace of columnar structure. This massive rock circles the tower as a bench extending out for 30 to 40 feet. It is strongly jointed, part into irregular prismatic forms, and part into rough, coarse layers. On the southwest face the long columns curve outward over the massive basal portion and lie nearly horizontal. The rugged pile of talus extends high up the lower slopes of the massive bench at the base of the tower, and also far down the adjoining slopes of the sedimentary rocks. In places it rises as a low ridge not far from the base of the tower, the fragments falling from the higher cliffs having bounded some distance away. At one point on the platform a short distance south of the tower, a low hill of porphyry shows a surface of 30 or 40 feet of massive rock, which may possibly be in place, and a low cliff of massive porphyry a few rods southeast of the base of the tower strongly suggests igneous rock in place.

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