GENESEE DRAINAGE BASIN. 207 



CHANGES OF DRAINAGE ON THE TRIBUTARIES. 



The chang-es of drainage in the southern portion of the basin are of 

 minor importance, and consist chiefly of slight incursions of the present 

 streams into the edges of the old valleys. These deflections are due to a 

 higher drift filling in the middle of these valleys than on the borders. In 

 some cases the lower ends of valleys were filled to a greater height than 

 the middle portions, thus forming morainal lakes in the middle portions. 

 In opening a passage to the Genesee these have in some cases cut down 

 into the old valley slope instead of into the deep part, and thus opened rock 

 ravines near the mouth. One of the most impressive of this class is found 

 on the lower course of Caneadea Creek below the village of Rushford, 

 where the morainal dam rises nearly 200 feet higher than the part of the 

 valley above it. 



In this headwater portion of the Genesee drainage basin the writer 

 has had opportunity to visit only a few of the passes that connect the 

 Genesee with streams discharging westward, and none of those discharging 

 eastward, and can not speak positively concerning shiftings of the divide. 

 The pass at Cuba appears to have its present divide several miles nearer the 

 Genesee than the old divide, there being a marked constriction in the valley 

 of Oil Creek several miles below Cuba which may mark the old divide. 

 The amount of drift is so great as completely to cover the old col if it stands 

 in this constriction. A stream entering Oil Creek from the south at Cuba 

 seems to have formerly dischai'ged northeastward to the Genesee at Belfast. 

 (See PI. V.) 



Fairchild has expressed the opinion that the headwater portions of 

 several of the tributaries of the Susquehanna in western New York formerly 

 discharged northward into the Lake Ontario Basin.^ Possibly the headwater 

 portion of Canesteo River discharged from Arkport northward past the low 

 divide at Burns into the Canaseraga Valley and thence to the Genesee. 



In the northern portion of the Genesee drainage basin the old lines of 

 discharge for tributaries evidently are not followed by the present lines. 

 The latter not infrequently are cutting trenches in the rocks, and in a few 

 cases have waterfalls. The filling with drift has completely concealed the 

 old drainage lines over much of the area drained by Black Creek and the 

 lower courses of Oatka and Honeoye creeks. 



'Bull. Geol. Soc. America, Vol. X, 1899, p. 30. 



