Naam: Vancauwenbergh
Voornaam: Jens
Groep: 1SA4
studiejaar: 2014-2015
Devils tower
Devils tower may seem a little bit like a loner in its place, protruding out of the rolling
prairie surrounding but it’s one of the most famous and distinctive natural landmarks of
the US. Because of the hundreds of parallel cracks on its surface, it’s Wyoming’s 867-foot
tall true magnet for climbers who come to ascend over 150 routes.
A rock that can talk back
The rock which forms Devils tower, is called Phonolite porphyry (fonoliet porfier), a rock
that intruded about 40.5 million years ago. Phonolite refers to the ringing of the rock
when a small slab is struck and it’s capability to reflect sound.
Porphyry refers to the texture of the rock where large crystals of feldspar are embedded
in a mass of smaller crystals.
The igneous material is recognizable with its light to dark-grey or greenish-grey color
with conspicuous crystals of white feldspar. The grey-greenish color is clearly visible on
the columns of Devils tower.
65 million years ago…
There is still no exact explanation of how Devils tower was formed over the years.
Geologists in the late 19th century came to the conclusion that it was formed by an
igneous intrusion. Modern geologists agree that it was formed by an igneous intrusion
and by glacial processes but not on exactly how it took place.
A popular theory in the early 20th century was that Devils tower had to be an eroded
remnant of a laccolith. Laccolith is a large mass of igneous rock which is intruded through
sedimentary rock beds without reaching the surface what causes a rounded bulge in the
sedimentary layers above.
Devils tower was formed by the same forces as the Rocky Mountains about 65 million
years ago. As magma rose through the crust, it intruded into existing sedimentary rock
layers and thereby lifting up the ground.
For millions of years, Devils tower wasn’t even visible until water and wind slowly eroded
the surrounding landscape, letting the igneous intrusion emerge. The softer materials,
like sandstone and shale, eroded away and the more resistant igneous rock survived.
Cultural theory
Devils tower is a climbers paradise but for the native Americans, the mountain is a
sacred place. Some of the Lakota people and other tribes aren’t fond of climbers who are
climbing Devils tower. They think they violate their sacred place. Others climb the
mountain themselves to be closer with the mountain.
For the native Americans, the mountain was a protection against a huge bear. As they
were running to high ground, the mountain rose up from the ground and this huge bear
was clawing to get to the villagers who were trying to escape. The native Americans
believe the clawing of the bear formed the columns of Devils tower.
Naam: Vancauwenbergh
Voornaam: Jens
Groep: 1SA4
studiejaar: 2014-2015
About the columns
The more geological explanation of the forming of the columns is slightly more extensive.
The laccolith intrusion, in this case phonolite porphyry with magma, started to cool off.
Hot molten magma is less dense than cool hardened rock and therefor occupies more
volume. As the rock cooled, it started to form hexagonal columns and contracted, making
the columns separated by vertical cracks. As glacial processes eroded the softer material,
the columns emerged from the ground.
Present and future
As of today, Devils tower has a height of 867-foot (264 meter). That’s almost as high as
the tallest residential building in the western hemisphere called New York in Manhattan.
Presumably, Devils tower once was a taller mountain than it is today. At the base you
can find huge piles of stones that are of the same material as the columns of the
mountain. Logically presuming that the columns once reached higher into the sky and
that Devils tower was slightly wider.
Eroding bit by bit
Devils tower will get smaller when time goes by. Rain and snow are eroding the mountain
bit by bit. The columns are extremely vulnerable to water and ice eroding.
When it rains, water is gathering between the cracks of the columns. That on its own will
not have a major effect on the columns but when the temperature drops below zero, the
water inside the cracks will begin to freeze. The water turns into solid ice which results in
an increase in volume.
When there’s not enough room between the cracks to provide this expansion, a force will
begin to build up against the columns. When this force is big enough it will overcome the
strength of the igneous rock, causing it to form cracks in its structure. These cracks
reduce the tension but it will also make the column to become unstable.
The columns will then reach a certain point when they are too unstable and chunks or
rock will fall off Devils tower.
The feldspar within the Porphyry will react with acid rain making the structure to fail and
hereby weathering the rock. In porphyry, the large crystals are embedded in a smaller
mass of crystals. When the crystals dissolve due to acid rain, the rock will begin to show
cracks, causing chunks of rocks to fall off.
After millions of years, even the hard igneous rock of Devils tower will be eroded to the
ground.
Naam: Vancauwenbergh
Voornaam: Jens
Groep: 1SA4
studiejaar: 2014-2015
Bibliography
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Wikiternative, Devils tower wiki. Internet,
(http://www.wikiternative.nl/uncategorized/devils-tower-wiki/)
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Een, Vlaanderen vakantieland Extra: Devils tower in wyoming, Internet, 2015,
(http://www.een.be/programmas/vlaanderen-vakantieland/extra-devils-tower-in-wyoming)

Klimetz P. M., Porphyry, Internet,
(http://earthphysicsteaching.homestead.com/Porphyry.html)
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Caryl-Sue, Devils Tower, Internet,
(http://education.nationalgeographic.com/education/media/devils-tower-geology/?ar_a=1)
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National Park Service, Geologic formations; Internet, 23/05/2015,
(http://www.nps.gov/deto/learn/nature/geologicformations.htm)
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Dezeen, New York by Gehry, Internet, 17/07/2011,
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De Bruijn Klaw W., New York by Hehry: deconstructing the tallest residential structure in the
West, Internet , 11/03/2011,
(http://sustainablecitiescollective.com/urban-sense/23627/new-york-gehry-deconstructingtallest-residential-structure-west)
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Ophardt, E. C., Which is more dense-Ice or Liquid Water?, Internet, 2003
(http://elmhcx9.elmhurst.edu/~chm/vchembook/122Adensityice.html)
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Robinson Charles S., Geology of Devils Tower National Monument Wyoming, Internet,
(http://pubs.usgs.gov/bul/1021i/report.pdf)