Preliminary report on the geology of east central Minnesota, including the Cuyuna iron-ore district, Bulletin 15, Plate 4
Description
Map and sections showing the geology and workings of the Pennington, Armour No. 1, and Armour No. 2 Mines, Cuyuna Iron-ore District, Minnesota, surveyed in July, 1915, scale 1 inch = about 130 miles.
Harder, E.C., Johnston, A. W. (A. Walfred) (1918). Preliminary report on the geology of east central Minnesota, including the Cuyuna iron-ore district, Bulletin 15, Plate 4. Minnesota Geological Survey. https://reflections.mndigital.org/catalog/mgs:978 (map)