Devils Tower National Monument
Devils Tower is a
monolith (more technically, an
igneous intrusion) or
volcanic neck located near
Hulett and
Sundance in eastern
Wyoming, above the
Belle Fourche River. It rises dramatically 1267 feet (386 m) above the surrounding terrain. Located at , the summit is 5112 feet (1558 m) above sea level.
It is part of the first
United States National Monument, established on
September 24,
1906 by President
Theodore Roosevelt. 1347 acres (5.45 km²) are included within the Monument's boundaries.
In recent years about 1% of the Monument's 400,000 annual visitors
climb Devils Tower. The monolith is featured prominently in the 1977 film
Close Encounters of the Third Kind.
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Devils Tower National Monument |
Tribes including the
Arapaho,
Crow,
Cheyenne,
Kiowa,
Lakota, and
Shoshone have had cultural and geographical ties to the monolith long before European and early American immigrants reached Wyoming. Their names for the monolith include: Aloft on a Rock (Kiowa), Bear's House (Cheyenne, Crow), Bear's Lair (Cheyenne, Crow), Bear's Lodge (Cheyenne, Lakota), Bear's Lodge Butte (Lakota), Bear's Tipi (Arapaho, Cheyenne), Tree Rock (Kiowa), and Grizzly Bear Lodge (Lakota).
In 2005, a proposal to recognize these ties through the additional designation of the monolith as Bear Lodge National Historic Landmark met with opposition from Rep.
Barbara Cubin, arguing that a "name change will harm the tourist trade and bring economic hardship to area communities" [
1].
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Red sandstone and siltstone cliffs above the Belle Fourche River |
Most of the landscape surrounding Devils Tower is composed of
sedimentary rocks.
The oldest rocks visible in Devils Tower National Monument were laid down in a shallow sea during the
Triassic period, 225 to 195 million years ago. This dark red
sandstone and maroon
siltstone, interbedded with
shale, can be seen along the
Belle Fourche River.
Oxidation of iron minerals causes the redness of the rocks. This rock layer is known as the Spearfish formation.
Above the Spearfish formation is a thin band of white
gypsum, called the Gypsum Spring formation. This layer of gypsum was deposited during the
Jurassic period, 195 to 136 million years ago.
Created as sea levels and climates repeatedly changed, gray-green shales (deposited in low-oxygen environments such as marshes) were interbedded with fine-grained sandstones,
limestones, and sometimes thin beds of red
mudstone. This composition, called the Stockade Beaver member, is part of the Sundance formation. The Hulett Sandstone member, also part of the Sundance formation, is composed of yellow fine-grained sandstone. Resistant to weathering, it forms the nearly vertical cliffs which encircle the Tower itself.
About 65 million years ago, during the
Tertiary period, the
Rocky Mountains and the
Black Hills were uplifted. Molten
magma rose through the
crust, intruding into the already existing sedimentary rock layers.
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Devils Tower National Monument |
Geologists agree that Devils Tower was formed by the
intrusion of
igneous material. What they cannot agree upon is how, exactly, that process took place. Geologists Carpenter and Russell studied Devils Tower in the late 1800s and came to the conclusion that the Tower was indeed formed by an igneous intrusion. Later geologists searched for further explanations.
In 1907, scientists Darton and O'Hara decided that Devils Tower must be an eroded remnant of a
laccolith. A laccolith is a large mass of igneous rock which is intruded through sedimentary rock beds but does not actually reach the surface, producing a rounded bulge in the sedimentary layers above. This theory was quite popular in the early 1900s since numerous studies had earlier been done on a number of laccoliths in the Southwest. The current popular theory, that the tower is an intrusive feature, does not really hold up under scrutiny. If the tower formed as an intrusion, then the columns should radiate out from the center instead of rising steeply.
Other theories have suggested that Devils Tower is a
volcanic plug or that it is the neck of an extinct volcano. Presumably, if Devils Tower was a volcanic plug, any volcanics created by it (volcanic ash, lava flows, volcanic debris) would have been eroded away long ago. Some pyroclastic material of the same age as Devils Tower has been identified elsewhere in Wyoming, so it is possible that the feature is volcanic in origin.
No one yet has a definite answer as to how exactly Devils Tower was formed, other than that it was an igneous intrusion into the sedimentary layers above; several geologists believe the molten rock comprising the Tower might not have surfaced; other researchers are convinced the tower is all that remains of what once was a large explosive volcano.
In any case, geologists agree that the igneous material intruded and then cooled as phonolite
porphyry, a light to dark-gray or greenish-gray igneous
trachyte rock with conspicuous crystals of white
feldspar. As the lava cooled,
hexagonal (and sometimes 4-, 5-, and 7-sided)
columns formed. As the columns continued to cool, vertical cracks developed as the columns shrank horizontally in volume (see also
Devils Postpile National Monument).
Until
erosion began its relentless work, Devils Tower was not visible above the overlying sedimentary rocks. But the forces of erosion, particularly that of water, began to wear away the sandstones and shales. The much harder igneous rock survived the onslaught of erosional forces, and the gray columns of Devils Tower began to appear above the surrounding landscape.
As rain and snow continue to erode the sedimentary rocks surrounding the Tower's base, and the Belle Fourche River carries away the debris, more of Devils Tower will be exposed. But at the same time, the Tower itself is slowly being eroded. Rocks are continually breaking off and falling from the steep walls. Seldom do entire columns fall, but on rare occasions they do. Piles of rubble - broken columns, boulders, small rocks, and stones - lie at the base of the Tower, indicating that it was, at some time in the past, larger than it is today.
Fur trappers may have visited Devils Tower, but they left no written evidence of having done so. The first documented visitors were several members of
Captain W. F. Raynold's Yellowstone Expedition who arrived in 1859. Sixteen years later,
Colonel Richard I. Dodge led a
U.S. Geological Survey party to the massive rock formation and coined the name Devils Tower. Recognizing its unique characteristics,
Congress designated the area a U.S. forest reserve in 1892 and in 1906 Devils Tower became the nation's first
national monument. Although proper
grammar would indicate that the monument be called "Devil's Tower," all
information signs and
references indicate "Devils Tower."
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East face of Devils Tower |
On
July 4,
1893, local rancher William Rogers became the first person to complete the climb after constructing a ladder of wooden pegs driven into cracks in the rock face. Technical rock climbing techniques were first used to ascend the Tower in 1937 when
Fritz Wiessner reached the summit with a small party from the
American Alpine Club. Today hundreds of climbers scale the sheer rock walls each summer; each lava column defines its own
climbing routes, whose difficulties range from easy to some of the hardest in the world. On some routes the gap between columns is just narrow enough to bridge with stretched-out legs, so the climber ascends doing "the splits" all the way. All climbers must register with a park ranger before and after attempting a climb.
American Indian legends tell of a few
Sioux girls who were picking flowers when they were chased by bears. Feeling sorry for them, the
Great Spirit raised the ground beneath the girls. The bears tried to climb the rock, but fell off, leaving their scratch marks on the sides.
Another version tells of how two
Sioux boys wandered far from their village when Mato the bear, a huge creature that had claws the size of teepee poles, spotted them, and wanted to eat them for a snack. He was almost upon them when the boys prayed to
Wakan Tanka the Creator to help them. They rose up on a huge rock, while Mato tried to get up from every side, leaving huge scratch marks as he did. Finally, he sauntered off, disappointed and discouraged. Wanblee, the eagle, helped the boys off the rock and back to their village.
The
1977 movie
Close Encounters of the Third Kind has a plot device which revolves around the tower.
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Devils Tower National Monument -
National Park Service
