270 H. L. FAIRCHILD — LAKE WARREN SHORELINES : GENEVA BEACH. 



The glacial lake Warren is believed to have covered all of the basin of 

 the present lake Erie, at least the southern part of the Huron basin, and 

 some portion of the western and southern part of the Ontario basin. 

 Until recently it was supposed that this water was broadly confluent 

 with the glacial lake occupying the Michigan basin and probably a por- 

 tion of the Superior basin, which latter lake had its outlet past the 

 present site of Chicago through the Des Plaines and Illinois rivers to 

 the Mississippi, and the name " Warren" was used to cover the entire 

 expanse. Later researches by Mr F. B. Taylor* indicate that the water 

 of the Michigan basin probably held a level somewhat lower than the 

 water in the Erie-Huron basin, and that the latter found escape across 

 the lower peninsula of Michigan by the Pewamo channel f and the val- 

 ley of the Grand river to the lower lake. Possibly the waters in the two 

 basins may have had nearly the same level and a connection by narrow 

 strait similar to that of the present lakes Michigan and Huron. In either 

 case the water in the Michigan basin requires a separate name, and the 

 name " Lake Chicago " has been proposed by Mr Leverett and concurred 

 in by the several geologists interested in this investigation (see page 52 

 of this volume). 



In former publications the writer has referred to evidences of deep 

 postglacial waters over the region of the Genesee valley and eastward 

 and assumed the presence of lake Warren. Even without the proof from 

 beaches the evidence of static water seemed sufficient. However, the 

 working hypothesis held by glacial geologists favored the opening of the 

 Mohawk outlet before the Ontario ice lobe retreated from the Lockport- 

 Batavia highland. In such event the Warren waters, imprisoned in the 

 Erie-Huron basin, would have been at once lowered toward the Iroquois 

 level (Mohawk-Hudson outlet) by the withdrawal of the ice-dam from 

 the Helderberg escarpment north of Batavia, and the Warren shoreline 

 would not extend east of that high land. The first search for Warren 

 beaches in the Genesee district was made in the spring of the present 

 year (1896) and with immediate success. The first discovery was of the 

 bars and spits near East Avon, which were traced eastward to Lima. 

 Later the beach was found at Morganville, east of Batavia, and traced 

 Doth eastward and westward. Finally the Warren beach at Crittenden 

 was taken as starting point and traced northward past Indian Falls and 

 about the tableland north of Batavia into connection with the shoreline 

 already followed westward from Morganville. 



* See Correlation of Krie-Huron Beaches with Outlets and Moraines in southeastern Michigan, 

 in this volume, pp. 31-58. 



f References to this old channel are found in papers by J. W. Spencer, Am. Jour. Sci., vol. 41, 

 March, 1891, p. 207 ; by K. H. Mudge, Am. Jour. Sci., vol. 50, December, 1895, p. 442, and by F. B. 

 Taylor, in this volume, p. 52. 



