WORK OF WINCH ELL, UPHAM AND MCGEE. 341 



rocks was foreshadowed in the writings of Keating and other explorers 

 already cited. 



N. H. Winchell in 1873 subdivided the series as follows, in ascending 

 order : 



3. Shakopee limestone ; 



2. Jordan sandstone ; 



1. Saint Lawrence limestone. 



In 1883 Warren Upham, in his study of the geology of Blue Earth 

 county,* was led to compare the stratigraphy of the Minnesota river val- 

 ley with that of the Mississippi. In this comparison (in the manuscript 

 referred to, on page 335, ante) the following series was determined : 



5. Shakopee A limestone ; 



4. Elevator B sandstone ; 



3. Shakopee B limestone ; 



2. Jordan sandstone ; 



1. Saint Lawrence limestone. 



The special item to note in the above is the discovery in Saint Paul, 

 during the boring of a deep well at Elevator 7>, of a layer of sandstone 20 

 feet in, thickness in the midst of the upper dolomitic member, the Shako- 

 pee. With some slight revising and a change in the names of two mem- 

 bers of Upham 's series, N. H. Winchell in 1887 adopted it and worked it 

 out in considerable detail f as the most probable sequence of the magne- 

 sian for this state. The change consisted in adopting the name " New 

 Richmond " for Elevator B and " Main body of limestone " for Shakopee B, 

 a term for which " Lower Magnesian limestone'' was subsequently used. J 



In the eleventh Annual Report of the United States Geological Survey 

 W J McGee discusses § the nomenclature of this series. On account of 

 the vagueness of Owen's descriptions, the obliteration by later investi- 

 gators of the upper members as they were outlined by him (see ante, p. 

 334) and the practical abandonment of the series, Mr. McGee adopts the 

 name Oneota for the middle member. Without tabulating, his classifica- 

 tion is as follows : the Shakopee A and Elevator B beds are the lower 

 portion of the Saint Peter of Iowa; the Jordan sandstone and the Saint 

 Lawrence dolomite and shale are the upper Potsdam of that state; while 

 the "Main body of Limestone" (Upham's Shakopee B) is the Oneota, 

 named after " the river upon which the rockmass finds its typical de- 

 velopment." || 



* Geology of Minnesota, Final Report, vol. i, 1884, pp H5-453. 



t< reology of Minnesota, Pinal Report, vol. ii, 1888, preface, p. xxii. 



X Ibid., pp. 12, 36, 72, etc. 



gThe Pleistocene Eistory of Northeastern towa (op. cit., 1892, pp. 187-577). The authors desire 

 express grateful acknowledgments to Mr. McGee for his gen irous loan of prool pages i tide, 



so far as thej referred to the Minnesota Paleozoic. 



|| Ibid., p. 833. 



