1. Geological map of Wisconsin, Iowa and Minnesota : exhibiting, also, the extension of the Iowa coal-field into Missouri, and its relation to the Illinois coal-field Maps University Of Minnesota Public content 1851. Owen, David Dale, 1807-1860. Engraved by W. Smith, Washn." Inset: "Geological map of the north shore of Lake Superior : on the scale of the original m.s. map. 110 x 66 centime...