Is devils tower a volcanic plug?

Devils Tower is an ancient volcanic plug, once covered by sediment. As volcanic rocks slowly cooled, isolated by sediments, large columns could form. Only subsequent erosion exposed the unusual shape of Devils Tower. However, some mysteries surround the formation of the columns.

Other theories have suggested that the devil's tower is a volcanic plug or that it is the neck of an extinct volcano. Presumably, if the Devil's Tower were a volcanic plug, any volcanic created by it volcanic ash, lava flows and volcanic debris would have eroded long ago. Some pyroclastic materials the same age as Devils Tower have been identified elsewhere in Wyoming. This formation was created when magma (volcanic rock molten inside the earth) was placed in place underground.

At the time the Devil's Tower was formed, the surface of the surrounding land was almost 915 m (3,000 feet) higher than it is today. After the magma hardened and cooled, the area eroded. There are two theories about how Devils Tower was formed. One theory holds that Devils Tower is a laccolito.

A laccolite is a large mass of igneous (volcanic) rock that penetrated through sedimentary rock beds, but did not actually reach the surface, producing a rounded bulge in the upper sedimentary layers. The other theory is that Devils Tower is a volcanic plug, or the neck of an extinct volcano. The composition of the volcanic material that forms Devils Tower suggests that the magma body was quite thick when it formed, which allowed it to maintain the shape it currently has. A thinner magma body would form a hard layer over a wider area that resists erosion and remains on a flat plateau.

But because it was relatively thick, the magma became a massive lump, forming its visible shape. The magma then solidified, preserving Devils Tower. This impressive igneous intrusion in northeastern Wyoming is 5112 feet (1558 m) above sea level. Devils Tower, the centerpiece of the Devils Tower National Monument, is actually a former volcanic plug.

As the magma in the neck of this volcano cooled, columns of similar size, mostly hexagonal, formed (photo below, can you find the climbers?) These columns are porphyry phonolite, composed of rather large feldspar crystals, approximately 0.5 or 1 cm in diameter. Devils Tower was the first national monument in the United States, established on September 24, 1906 by President Theodore Roosevelt. The Devil's Tower did not visibly protrude from the landscape until the overlying sedimentary rocks eroded. Some of these wooden stakes are still intact and are visible in the tower when walking the 1.3 mile (2.1 km) Tower Trail at the Devils Tower National Monument.

As rain and snow continue to erode the sedimentary rocks surrounding the base of the Tower, more Devils Tower will be exposed. The columns of Devils Tower are almost the same height, suggesting that the whole had been a single pool of magma, but fractured into separate columns as it cooled. Many believe that the molten rock that comprises the Tower may not have surfaced; others are convinced that the tower is all that remains of what was once a large explosive volcano. The columns of Devils Tower, which rise hundreds of feet in the air and extend up to 10 feet wide, are truly spectacular.

Eventually, the receding waters divided into large canals that cut deep valleys and, in this case, formed the Belle Fourche River Valley and exposed the Devils Tower. Geologists agree that Devils Tower began as magma, or molten rock buried beneath the Earth's surface. Devils Tower was the first declared national monument in the United States, established on September 24, 1906 by President Theodore Roosevelt. The Tower's harder igneous rock is more resistant to erosion, and the gray columns of the Devil's Tower began to stand out above the surrounding landscape.

Wooden Leg, a Cheyenne from the north, recounted another legend told to him by an old man as they traveled together through the Devil's Tower between 1866 and 1868.Ironically, the erosion exposed by the Tower also erased the evidence needed to determine which theory of the formation of the Devil's Tower is the right one. . .

Roxanne Cotner
Roxanne Cotner

Incurable music nerd. Amateur pop culture specialist. General internet aficionado. Unapologetic web lover. Hipster-friendly bacon fanatic.