"[Lot of 2] Geological Map of the District Between Keweenaw Bay and Chocolate River. Lake Superior Michigan [and] Geological Map of Isle Royale Lake Superior, Michigan", Foster/Whitney
Subject: Lake Superior, Michigan
Period: 1850 (circa)
Color: Hand Color
A. Geological Map of the District Between Keweenaw Bay and Chocolate River. Lake Superior Michigan, (24.3 x 19.6"). This detailed geological map covers the region from the Keweenaw Bay to the Chocolate River. A color-coded key locates seven geological units, including sandstone, quartz, limestone, schistose and trappean rocks, granite and basalt. There is also good detail of relief shown in hachure. A scale below the title converts chains to miles. Fancy title lettering. Condition: Issued folding with light offsetting, a few spots of foxing, light toning especially concentrated at top and along a fold at left, and a tiny split at one of the fold intersections. Portions of the neatline have been trimmed away at top.
B. Geological Map of Isle Royale Lake Superior, Michigan, (24.9 x 17.6"). This early geological map updates Charles T. Jackson's map of 1847 and was completed after J.W. Foster and J.D. Whitney took over the Survey of the Mineral Lands of Michigan in 1850. It locates Sandstone, Conglomerate and "Trap: Basalt, Porphyry" formations with three different colors. Legend keys Mines, Abandoned Mines, Mineral Land Supposed to Contain Copper, Furnace, and more. Condition: Issued folding with some toning at left, minor offsetting, and a few short tears including one along the border at left.
References: Karpinski (MI) #764 & 787; Marcou & Marcou #365 & 369.
See description above.