354 



BOTANICAL GAZETTE 



[NOVEMBE 



development of reentrant angles along its crest, as the great con- 

 tinental ice sheet 2 became more and more differentiated into lobes 

 during its retreat (52, 13). In northern Indiana it marks the first 

 areas uncovered, as the mass of ice, pushed forward from the basin 

 of Lake Michigan, separated from that originating in the Lake Huron 

 and Lake Erie basins. 



When the Huron River basin was reached, the Saginaw lobe had 

 been developed and lay over the northwestern part, while the Huron- 

 Erie lobe covered all of the territory southeast of the interlobate 



FIG. 2. Map of southern Michigan, northern Indiana, and northern Ohio, 

 showing "moraines with strong expression." After LEVERETT, U. S. Geol. Surv. 

 Mon. 41, plate 2. The irregular dotted lines mark the looo-foot (300) contour. 



moraine. The first portion of our area to be uncovered is the triangu- 

 lar gravel outwash apron extending southwestward from Sugarloaf 

 Knob. This was the beginning of the Huron River. Kavanaugh 

 Lake then lay just under the edge of the Erie ice, and Crooked Lake 

 occupied a similar position on the southern border of the Saginaw 

 lobe. As has been recently determined by Mr. FRANK LEVERETT, 

 of the U. S. Geological Survey, the subsequent history of the Huron 

 drainage is most remarkable. 



The waters from the glacial drainage at first flowed generally 

 westward, reaching the Kalamazoo River near Albion, thence to the 

 St. Joseph at Three Rivers. At South Bend, Indiana, it crossed 



2 For general map see no. 55, p. 411. (Bibliography at close of this paper.) 



