Iowa

• Crystal Lake Cave
• Maquoketa Caves SP
• The Grotto of the Redemption
• Spook Cave

Literature

• Greg A Brick (2004): Iowa Underground, A Guide to the state's subterranean treasure. 223 pp, illus. SB
  Brick is Professor of Geology at Normandale College in Bloomington, Minnesota. His book will reveal the state's subterraean attractions including show and wild caves, springs, mining sites and other geological and man-made sites. A uniquely written perspective by a premier Midwest cave historian.

• See also
• Lead and Zinc Mines of Dubuque, Iowa by James S. Dockal