This early geological survey presents the area between Prairie du Chien (here Fort Crawford and Kipy Saging), north along the Mississippi River to beyond Duluth, and extends east to include the rapids along the northern reaches of the Wisconsin River. A legend in the lower right explains the use of color to indicate the twelve different geological formations. This uncommon map was prepared to illustrate David D. Owen's report. Owen and his staff are reported to have worked 12-15 hours every day during the summer and winter of 1847 to complete this notable survey.

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Condition: B

Nice impression and original coloring. Issued folding, now pressed and backed with archival tissue. Some light toning along folds, else very good.