Although the 50-million-year-old tower is composed of hard igneous rock, much of the other exposed rock within the 1,347-acre monument is made of soft sediments from the warm, shallow seas of the Mesozoic era. These colorful bands of rock encircling the igneous core include layers of sandstone, shale, mudstone, siltstone, gypsum, and limestone.

The story of Devils Tower's geology is but one chapter in the history of the Black Hills. Even now, after extensive study and detailed geologic mapping, modern scientists are still debating the origins of Devils Tower. While scientists agree it is an igneous (or volcanic) intrusion, their theories diverge on the tower's original size and shape. The most popular suggests that it is the result of volcanic activity in the early Tertiary period, some 50 million years ago. Scientists believe that a mass of molten rock forced its way up from below the surface of the earth, forming an inverted, cone-shaped structure beneath layers of sedimentary rock in what is now northeastern Wyoming. As the molten rock slowly cooled, it cracked and fractured, creating one of the most striking features of the monument, its polygonal columns. Most of the columns are five-sided, and others are four- or six-sided. The largest columns measure 15 to 20 feet in diameter at their base and gradually taper upward to about 10 feet in diameter at the summit.

Over centuries, the gentle waters of ancient streams and rivers carried away sedimentary layers, leaving the more erosion-resistant igneous rock behind. Today the tower appears to sit quietly on the crest of a wooded hill, but its base is actually the top of the unexposed magma, covered with fallen columns and soil.

American Indian Legend

American Indians have their own names for Devils Tower, which earned its current moniker from a translation of "bad god's tower." Since long before 1875, the Lakota have called it Mato Tipila, or Grizzly Bear Lodge, and descendants of several American Indian nations of the Great Plains share similar legends of how the prominent butte was formed.

According to the Kiowa version of the tale, seven sisters watched with horror as their brother was turned into a bear. The sisters ran from him to the stump of a large tree, which beckoned them to climb on. (In other versions, they ran to a large, flat stone.) When they did, the stump rose up into the sky, and the bear, unable to climb up the stump to reach the sisters, scored it with its claws. The sisters were then raised into the sky, becoming the seven stars of the Big Dipper.

Devils Tower is a sacred place to many native peoples. In deference to the religious significance of the tower, the National Park Service has requested that climbing of the tower be voluntarily suspended during the month of June so that ceremonies may be conducted without interference.

First Ascent

As a battle to preserve the monument from commercial encroachment was being waged in 1893, two local ranchers decided it was time someone made the first recorded climb to its summit.

William Rogers and Willard Ripley planned for months before making their first attempt on the southeast face on July 4, 1893. As the date approached, the pair began distributing handbills offering such amenities as ample food and drink, daily and nightly dancing, and plenty of grain for horses. The flyers also touted the feat as the "rarest sight of a lifetime."

Rogers and Ripley used a wooden stake ladder for the first 350 feet of the climb. As more than 1,000 spectators watched, the pair made the harrowing climb in about an hour, raised Old Glory, and then sold pieces of it as mementos of the occasion. Thereafter, the tower became a popular place for Independence Day family gatherings. At the annual affair in 1895, Mrs. Rogers used her husband's ladder to become the first woman to reach the summit.

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