REVISION OF THE MAP OF LAKE AGASSIZ 



WARREN UPHAM 



Minnesota Historical Society, St. Paul, Minnesota 



After the lapse of twenty years since the completion of my 

 official service on the geological surveys of Minnesota and the 

 United States, it is not surprising that changes and additions have 

 been made, and that others are needed, on maps of the glacial and 

 modified drift formations and the successive shorelines of the 

 glacial Lake Agassiz, as these were published in the reports of my 

 work from 1879 to 1895. Therefore the recent Bulletin 12 of the 

 Minnesota Geological Survey,^ entitled "Surface Formations and 

 Agricultural Conditions of Northwestern Minnesota," by Mr. 

 Frank Leverett, of the United States Geological Survey, has much 

 interested me. 



One of the most noteworthy additions here made to our knowl- 

 edge consists in the more accurate description and mapping of the 

 somewhat elevated large tract between Red Lake and the Lake of 

 the Woods, which was named by me Beltrami Island.^ My ori- 

 ginal description and map of this island were doubted and ques- 

 tioned by Professor James E. Todd in 1899 ;3 and they have now 

 been shown by Mr. Leverett, with more defaiite surveys, including 

 information of exact altitudes throughout this area, to need impor- 

 tant revision. 



A line surveyed about the year 1892 for the Duluth & Winnipeg 

 Railroad Company took a straight northwesterly course from the 

 most northeastern part of the shore of Red Lake to the most south- 



' This report, 78 pages, with 8 plates (a folded map and views from photographs) 

 and 14 figures in the text (maps and diagrams), was published by the University of 

 Minnesota in February, 1915, under Professor William H. Emmons, director, in 

 co-operation with the United States Geological Survey. It includes also a chapter on 

 ' ' Climatic Conditions in Minnesota," by U. G. Purssell, United States weather observer 

 in Minneapolis. 



"" Am. Geologist, XI (June, 1893), 423-25; "The Glacial Lake Agassiz," 1896, 

 U.S. Geol. Survey Man. XXV, 304-06, with mapping on Plates III, X, etc. 

 3 Geology of Minnesota, IV, 149-50. 



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