MINOR TEIBUTARIES OF LAKE ONTARIO. 209 



the First Warsaw and the Second Warsaw glacial lakes. At the seventh 

 stage of the glacial Genesee waters the ice barrier became removed suffi- 

 cientl}^ to lower this lake to the level of tlie Genesee waters and thus bring 

 its distinct history to a close.^ 



Fairchild has also found evidence of the existence of small glacial 

 lakes in the headwaters of eastei'n tributaries of the Genesee that discharged 

 to the Susquehanna at higher levels than the outlet past Burns. These and 

 the glacial lakes held in the valleys of the Finger Lakes to the east of the 

 Genesee have furnished him the material for a ver}^ interesting chapter of 

 glacial history, but they lie outside the district covered by the present 

 report. The four papers already published by Fairchild in the Bulletin of 

 the Geological Societ}^ of America^ describe in detail much that can be 

 only briefly summarized here. 



MINOR TRIBUTARIES OF LAKE ONTARIO IN WESTERN NEW YORK. 



Oak Orchard Creek is the most important southern tributary of Lake 

 Ontario between the Genesee and Niagara ]-ivers. Its headwater j^ortion 

 lies on the plain between the Niagara and Corniferous limestone escarp- 

 ments immediately west of the headwaters of Black Creek and drains 

 portions of Genesee and Orleans counties. In southwestern Orleans County 

 it turns northward through the Niagara escarpment, near Medina, where it 

 has a series of falls, and then takes a northeastward course into Lake Ontario. 

 The falls, tliree in number, a section of which appears in Hall's report on 

 the Fourth district, occur in the passage over the Medina sandstone and 

 Clinton limestone, as well as at the Lockport (Niagara) limestone. It is 

 doubtful if the stream in any ^jart of its course follows a preglacial drainage 

 line, for the portions in which it is free from rapids and cascades are in 

 plains heavily covered with drift. The headwater portion is exceedingly 

 sluggish and is bordered by swamps, which have required a large amount 

 of artificial drainage. 



The remaining tributaries of Lake Ontario in western New York head 

 in the Niagara escarpment and flow usually more or less directly across the 

 plain between that escarpment and the lake. Johnsons Creek, however, 



1 Bull. Geol. Soc. America, Vol. X, 1899, pp. 33-34. 



' Glacial lakes of western New York, Vol. VI, 1895, pp. 353-374. Glacial Genesee lakes. Vol. VII,, 



1896, pp. 423—152. Lake Warren shore lines in western New York and the Geneva beach. Vol. Vn\, 



1897, pp. 269-286. Glacial waters in the Finger lakes region of New York, Vol. X, 1899, pp. 27-68. 



MON XLI IJ- 



