Fire in the Hole! EarthCache
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Fire in the Hole!
Welcome to the oldest and deepest iron ore mine in Minnesota.
Soudan UMSP has an interesting geologic history. The underlaying bedrock formations in the park are
estimated to be more than 2.7 billion years old. The two bedrock formations are an iron-bearing
metamorphic formation and a metamorphosed sedimentary rock formation. These iron-bearing formations
were created by volcanic activity at the bottom of an ancient ocean, the same type of activity observed
around hydrothermal vents and suboceanic volcanoes on the ocean floor today.
The iron ore of the Vermilion Range district was first “discovered” in 1850, although there is evidence of
quarrying for jasper and other minerals by American Indians that predate European settlement. Substantial
exploration for iron did not start until 1875. The ore bodies within the park are irregular in shape and are
mostly hard and dense blueish hematitie and are of exceptionally fine material. The principal iron minerals
of these ores are blue and dark red hematites with minor amounts of magnetite and siderite. The area was
extensively mined however substantial deposits remain. Deposits of other minerals such as nickel, lead,
gold, silver and zinc are likely present.
In the late 1800s, prospectors searching for gold in northern Minnesota discovered extremely rich veins of hematite at this site, often containing more than 65% iron. An open pit mine began operation in 1882, and moved to underground mining by 1900 for reasons of safety. By 1912 the mine was at a depth of 1,250 feet (381 m). When it closed, the lowest level was being developed at 2,341 feet (713.5 m) below the surface.
The primary underground mining method used was known as cut and fill. This involved mining the ceiling and using Ely Greenstone and other waste rock to artificially raise the floor at the same rate as the ceiling was being mined out. As a result the floor and ceiling were always 10-20 feet (3-6 m) apart, and waste rock never had to be hauled to the surface, since it was recycled.
The surface buildings are open to the public, and during the summer months there are daily tours of the mine. Visitors are lowered in an 80-year-old electric mine hoist to the mine's lowest level at 2,341 feet (713.5 m) below ground. Two tours are open to the public: one that explores the historic mining facilities, and another that focuses on the currently active underground physics laboratory.
Visitors wear hard hats and journey down 2,341 feet via a "cage." On the lowest level, the transportation shifts to a rail car for a ride back into the mine as you listen to the stories of the mining days. Above ground visitors can explore the dry house, drill shop, crusher house and engine house. Visitors also can walk the boardwalk past one of the deepest open mine pits or hike the trails in the park through a northern hardwood conifer forest, past the famous Soudan Iron Formation.
The second attraction is the High Energy Physics Lab. The Underground Laboratory is the leading deep underground science and engineering laboratory in the United States today. Scientists from around the world have been working at Soudan for 25 years trying to answer basic questions about the Universe in which we live: Is matter completely stable? What is the nature of the fundamental forces? Can we identify the Dark Matter that seems to permeate our Universe? Learn about our first neutrino events using the neutrino beam from Fermilab and see the massive MINOS detector (Main Injector Neutrino Oscillation Search). Learn about CDMS (Cryogenic Dark Matter Search) and its continued search for a WIMP (Weakly Interacting Massive Particles).
Tours of the mine and Physics Lab are available to the public for a fee. The tours are only open from late May until Labor Day. Please contact the mine at:
Soudan Underground Mine State Park
P.O. Box 335
Soudan, MN 55782
(218) 753-2245
soudanmine@dnr.state.mn.us
To get credit for this cache visit the site and E-mail me the answers to the following questions:
1.) What is the lowest level # the miners worked?
2.) What is the temperature of the air at the lowest level?
3.) According to the sign in front of you who operated this mine until 1962?
Please do not post answers in your logs.
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