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Lake Vermilion-Soudan Underground Mine State Park

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TheLake Vermilion-Soudan Underground Mine State Parkis aMinnesotastate parkat the site of theSoudan Underground Mine,on the south shore ofLake Vermilion,in theVermilion Range (Minnesota).The mine is known as Minnesota's oldest, deepest, and richest iron mine. It formerly hosted theSoudan Underground Laboratory.As theSoudan Iron Mine,it has been designated a U.S.National Historic Landmark.

Soudan Iron Mine
The 27th level of the Soudan Mine
Lake Vermilion-Soudan Underground Mine State Park is located in Minnesota
Lake Vermilion-Soudan Underground Mine State Park
Lake Vermilion-Soudan Underground Mine State Park is located in the United States
Lake Vermilion-Soudan Underground Mine State Park
LocationTower-Soudan State Park,Breitung Township, St. Louis County, Minnesota
Nearest cityTower, Minnesota
Coordinates47°49′24″N92°14′14″W/ 47.82333°N 92.23722°W/47.82333; -92.23722
Area122 hectares (301 acres)
Built1900
WebsiteLake Vermilion-Soudan Underground Mine State Park
NRHP referenceNo.66000905[1][2]
Significant dates
Added to NRHPNovember 13, 1966[1]
Designated NHLNovember 13, 1966[3]

History

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Lake Superior Iron Ranges
The headframe for shaft #8, still in active use today

In the late 19th century, prospectors searching for gold in northern Minnesota discovered extremely rich veins ofhematiteat this site, often containing more than 65% iron. An open pit mine began operation in 1882, and moved to underground mining by 1900 for safety reasons. From 1901 until the end of active mining in 1962, the Soudan Mine was owned by theUnited States Steel Corporation'sOliver Iron Mining division.By 1912 the mine was at a depth of 1,250 feet (381 m).[4]When the mine closed, level 27 was being developed at 2,341 feet (713.5 m) below the surface and the entire underground workings consisted of more than fifty miles ofdrifts,adits,andraises.In 1965, US Steel donated the Soudan Mine to the State of Minnesota to use for educational purposes.[5]

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. There was no need to move waste rock to the surface, because it was moved short distances and left in place. This technique was particularly suited to the Soudan Mine due to the strength of the hematite formations and the weakness of the encasing Greenstone. This method was not possible in the nearby mines inEly, Minnesota,because the iron formations there were fractured and thus were not as structurally stable as those at Soudan.[citation needed]

State park

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The park is inBreitung Township,on the shore of Lake Vermilion in northern Minnesota'sVermilion Range.It has become a popular tourist site, often visited on the way to and from Ely and theBoundary Waters Canoe Area Wilderness.[citation needed]

The state park is operated under theDepartment of Natural Resources.It is aNational Historic Landmark,meaning that it is also listed on theNational Register of Historic Places.[3]As of 2021, the surface buildings are open to the public, and during the summer months there are daily tours of the mine.[6]Visitors are lowered in the antique 1924 electricmine hoistto level 27, the mine's lowest level at 2,341 feet (713.5 m) below ground.[7]As of 2021, tours of the previously active underground physics laboratory were no longer offered.[8]

Lake Vermilion State Park, originally separate from Soudan Underground Mine State Park, began with the purchase of about 3,000 acres fromU.S. Steelin 2010.[9][10][11]The park includes theStuntz Bay Boathouse Historic District.[12]In 2014, the two adjacent parks were combined into one.[13]

Underground laboratory

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MINOS Detector
Surface outcrop, folded Soudan Iron-Formation, age about 2.69 billion years. Scratches are from glaciation.

In the 1980s, scientists from theUniversity of Minnesotabegan to develop the Soudan Mine as a site for sensitive physics experiments because of the very low rate ofcosmic raysin the deep underground site, and also because they could inexpensively use the still-operating mine hoist. The mine laboratory was originally home to theSoudan 1proton decayexperiment and its successor,Soudan 2which operated from 1989-2001.[14]The University and the Minnesota Department of Natural Resources later expanded the laboratory to accommodate other physics projects, such as theMINOSneutrinodetector,dark mattersearch experimentsCDMS-II, SuperCDMS, andCoGeNT,as well as work onelectroformingcopper to create pure radiation-free copper. Low-background materials screening facilities were in use and in continuing development.[15][16]The mine was proposed as one possible site for a U.S.Deep Underground Science and Engineering Laboratory,but that project was instead awarded to theHomestake Mine (South Dakota).[citation needed]Parts of the laboratory had been open for daily tours, and there was an annual open house with more access to the facilities and representatives of the experiments to help with the tours and answer questions.[17]The laboratory, along with public tours, were closed circa 2016.[8][15][18]

2011 fire

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A fire broke out late on March 17, 2011, in the main shaft at the 25th level.[16]The fire was smothered using 70,000 gallons of fire-fighting foam, filling the 27th and lowest level of the shaft (27th level) from floor to ceiling. The Underground Laboratory lost power but remained safe. The mine tours were closed for the summer of 2011, but the above ground tours and interpretive center reopened. After a major cleanup effort, underground tours resumed on May 26, 2012.[17]

See also

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References

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  1. ^ab"National Register Information System".National Register of Historic Places.National Park Service.July 9, 2010.
  2. ^Stephen Lissandrello (January 3, 1976)."National Register of Historic Places Inventory-Nomination: Soudan Underground Mine State Park"(pdf).National Park Service.{{cite journal}}:Cite journal requires|journal=(help)andAccompanying 8 images from 1975.(897 KB)
  3. ^ab"Soudan Iron Mine".National Historic Landmark summary listing.National Park Service. Archived fromthe originalon June 12, 2012.RetrievedSeptember 8,2009.
  4. ^Van Barneveld, Charles E. (1913)Iron Mining in Minnesota,199. University of Minnesota.
  5. ^Richard W. Ojakangas; Charles L. Matsch (1982).Minnesota's Geology.University of Minnesota Press. pp.127–130.ISBN0816609535.
  6. ^"Soudan Underground Mine Tours".Minnesota Department of Natural Resources. 2021.RetrievedDecember 26,2021.
  7. ^Pointer, James (2009).Engine House Audio Tour Chapter 12, Stop 11.Minnesota Department of Natural Resources.
  8. ^ab"Virtual Tour".University of Minnesota Soudan Underground Laboratory. 2012.RetrievedDecember 26,2021.
  9. ^Park InfoArchived2014-01-16 at theWayback Machine,Minnesota Department of Natural Resources.
  10. ^Cooperative Master Plan: Lake Vermilion State Park, Soudan Underground Mine State Park, 2011–2020,Minnesota Department of Natural Resources Division of Parks and Trails (December 2010). Master plan for development of parks.
  11. ^Lake Vermilion and Soudan Underground Mine State Parks,Minnesota Department of Natural Resources map of two parks indicated separately
  12. ^Ross, Jenna (September 18, 2020)."These 143 historic boathouses offer a peek into Minnesota's past".Star Tribune.RetrievedDecember 26,2021.
  13. ^Laine, Mary (June 1, 2016)."Once Minnesota's deepest mine, Soudan complex is now a state park".MinnPost.RetrievedDecember 26,2021.
  14. ^"High Energy Physics Lab".Minnesota Department of Natural Resources. Archived fromthe originalon June 29, 2011.RetrievedApril 19,2011.
  15. ^ab"Lab History: Why Underground?".University of Minnesota Soudan Underground Laboratory. 2012.RetrievedDecember 26,2021.
  16. ^ab"Scientists reenter Soudan Underground Laboratory".Fermilab Today.RetrievedAugust 9,2015.
  17. ^ab"Closed by fire, Soudan Underground Mine State Park resuming tours".St. Paul Pioneer Press.May 22, 2012.RetrievedDecember 26,2021.
  18. ^Kazcke, Lisa L. (March 3, 2018)."Work continues to find tenants for Soudan underground lab".Duluth News Tribune.RetrievedDecember 26,2021.
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