;j36 The American Geologist. May, 1897 
with varying results, mihI unless better uniformity prevails 
soon, exact correlation with the Ordovician of New York state 
may be called a failure, and a local classification and nomen- 
clature must be preserved intact. Further, it may be suggested 
that no one thing will be a greater aid in establishing the de- 
sired correlation with other areas than will a locally exact 
and uniforml}^ applied system of nomenclature under which 
to assemble the accumulating evidence. 
THE AGE OF THE GREAT LAKES OF NORTH 
AMERICA.* 
^4 Partial Bibliography, with Notes. 
By Alexander N. Winchell. 
1863. A.C.Ramsay: "On the Glacial Origin of certain 
Lakes in Switzerland," etc., Amer. Jour. Sci., Ser. II, vol. 
XXXV, p. 324 ; in footnote, p. 342, Ramsay agrees with Sir 
Wm. Logan in ascribing the great lakes to the action of gla- 
ciers. 
1871. N. H. Winchell : "The Glacial Features of Green Bay 
of Lake Michigan, with some observations on a probable for- 
mer outlet of Lake Superior," Amer. Jour. Sci., Series III, vol. 
II, p. 15; on p. 19. Winchell assumes the existence of lake 
Superior in Tertiar^^ times. 
1872. Charles Lyell: ''Principles of Geology," 11th ed., 
vol. I, p. 418; Lyell believes in a partial pre-glacial origin for 
the great lakes. Instance the following words, speaking of 
lake Superior: "If we are compelled to grant that such ine- 
qualities of movement have occurred in post-glacial times, we 
may well suppose that others of far greater extent contributed, 
before and during the Glacial period, to form the basin of the 
great lake itself." 
1874. J. S. Newberr}'-: "Surface Geology of Ohio," Report 
of Geol. Survey of Ohio, Geology, vol. ii, p. 72, and other 
places. Dr. Newberry seems to have hazy ideas on the origin 
of the great lakes, and, in trying to make definite statements, 
apparently contradicts himself, as for example, in the follow- 
ing extracts : 
*Read before the Geological Club of the University of Minnesota: 
meeting, October 17, 1896. 
