376 PLEISTOCENE OF INDIANA AND MICHIGAN. 



The eastern barrier lay in the basin of Lake Ontario, in the western half conforming rather 

 closely to the outline of the present lake but in the eastern half expanding over the higher 

 ground. Narrow arms of Lake Arkona reached eastward beyond the Genesee Valley and 

 around the north side to a point north or northeast of Toronto. The evidence now available 

 indicates that the barriers of Lake Arkona stood in about the same position as for Lake Warren, 

 the former marking a climax of retreat and the latter a climax of readvance. 



On the other hand, retreat for much more than 25 miles would have opened lower outlets 

 at other points. At the next climax of retreat this happened and the lake level fell below the 

 head of the Grand River channel, forming the Wayne beach and draining eastward past Syra- 

 cuse, N. Y. 



Thus, while the place of the ice barriers of Lake Arkona can not be definitely determined 

 by direct evidence, there are rather definite limits beyond which the barriers can not have re- 

 treated without opening new outlets and lowering the lake. The approximate position of the 

 western ice barrier of Lake Arkona is shown in figure 6 (p. 370). The positions of the eastern 

 barriers of Lakes Whittlesey and Warren are shown in a diagram on page 18 of the Niagara 

 folio, 1 and the probable positions of the barriers of Lakes Arkona and Wayne in that region 

 are discussed in connection with glacial Lake Wayne. (See p. 391.) 



CORRELATIVES OP LAKE ARKONA. 



Lake Chicago had attained nearly its maximum size as an independent lake at the time of 

 Lake Arkona, but Lake Duluth had not yet come into existence. In New York most of the 

 Finger Lakes had united with Lake Arkona, but probably the more easterly ones had not. 



i Niagara folio (No. 190), Geol. Atlas U. S., U. S. Geol. Survey, 1913. 



