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L20 Volcanic Neck. Devil's Tower National Monument, Wyoming, USA
Position:
N34° 35'
W104° 40' approx.
Elevation:
5112' / 1558m at the summit ; 4245' / 1293m at the base
Image format:
MF 35mm
VOLCANIC NECK
This structure was part of an ancient VOLCANO about 60 million
years ago. Hot, liquid MAGMA from within the crust was forced
into the SEDIMENTARY rocks near the surface. Over millions of
years the rock slowly cooled and shrank as it occupied less space.
Cracks developed along regular lines during the shrinkage process.
The regular system of cracks can now be seen as a collection of
columns each with five, six or seven straight sides. Similar polygonal
rock structures can be seen in many localities all over the world,
including the Devil's Post Pile in California (L79) and the Giant's Causeway in Northern Ireland, UK (L80).
The use of words like "Devil" and Giant" typifies the powerful
symbolism that these structures generate as "wonders" and "mysteries".
The Devil's Tower rises 867' / 264m above the plain and dwarfs
the trees of the surrounding pine forest. It can be seen from
many miles /kilometers away over the Northern Plains of eastern
Wyoming and from South Dakota's Black Hills. Understandably, the
Tower is of important to several Native Tribal American cultures
among the Great Plains Indians. In recent times the Tower was
featured in the highly successful sci-fi movie "Close encounters
of the third kind".
The tower is popular among rock climbers. The first recorded ascent
to the top was in 1893.
Less detail
Image Trail:
L6 Volcanic neck and dyke. Ship Rock. New Mexico, USA
L7 Igneous dyke radiating out from volcanic neck. Ship Rock. New
Mexico, USA
L19 Volcanic Neck. Devil's Tower. National Monument. Wyoming, USA
L48 Granite dykes intruding slate. Cornwall, USA
L49 Dormant volcano. Mt Shasta. California, USA
L52 Igneous dyke intrusion. Convict Lake. Cornwall, USA
L79 Glacial Polish on polygonal basalt, Devil's Post Pile, California,
USA
L80 The Giant's Causeway, Co. Antrim, Northern Ireland, UK
Links: www.volcano.und.nodak.edu/vwdocs/Parks/devils_tower/devils_tower.html
http://geography.com.sg/tectonics/index.html
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