This early geological survey extends from Prairie du Chien (here also Fort Crawford and Kipy Saging) north along the Mississippi River to the Minneapolis area and beyond to Duluth. The eastern range includes the rapids along the northern reaches of the Wisconsin River. A legend at lower right explains the use of color to indicate twelve different geological types. This map was prepared to illustrate David D. Owen's report on his geological reconnaissance. Owen and his staff were reported to have worked 12-15 hours every day during the summer and winter of 1847 for this notable survey.

References: Marcou & Marcou #451.

Condition: B

Issued folding with contemporary color. There is light toning along the folds, a few faint tape stains, and a couple of small chips in the blank margins. Now pressed and backed with archival tissue to repair some short fold separations and minor tears.