South Dakota School of Mines Bulletin No. 13. Plate No. 6. 





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MAI'oi NEBRASKA 



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Reproduction of Hayden's Earliest Geological Map of the Upper Missouri 

 country. The original map is colored to show the several rock divi- 

 sions as then Known. Note the erroneous extension of the Black 

 Hills to the Yellowstone river, Hayden, 1857. 



