142 H. L. FAIRCHLLD PLEISTOCENE GEOLOGY OF NEW YORK STATE 



the northern part of the continent in Tertiary time seems to be a fact 

 and accompanied by warm climate. If necessary to explain phenomena 

 we may assume effective vertical movements in our region. The Tertiary 

 was certainly a time of vigorous drainage and remarkable valley-cutting 

 in northern lands. When the fiord valleys were making in other lands 

 what was doing here ? Undoubtedly our rivers were also active, and the 

 deep valleys of central Xew York are one result. 



At the last Baltimore meeting of the Society the writer exhibited a 

 series of maps suggesting the drainage evolution in Xew York. 7 The 

 high "hung-up" valleys, with northeast by southwest direction, and 

 mostly without present streams, seem to be an inheritance from the 

 primitive drainage on the new land surface. The drainage lines of the 

 upper tributaries to the Delaware and Susquehanna rivers preserve their 

 original direction. During some pre-Pleistocene time the development 

 of subsequent valleys along the strike of the thick and weak Ontario 

 strata resulted in a great east and west valley carrying a great trunk 

 stream, the hypothetical Ontario River. Into .this valley was drawn from 

 the south, as obsequent streams, all the drainage of western and central 

 Xew York and the adjacent territory of northern Pennsylvania. The 

 Susquehanna Eiver turned northward at Elmira and occupied the Seneca 

 Valley, which probably accounts for the excessive depth of the valley, a 

 drilling at Watkins of 1,200 feet failing to reach rock. The Genesee 

 River is the one stream which fully represents the preglacial northward 

 flow, having held its northward direction clear across the State in spite 

 of the tendency of glaciation to force it into southward flow. All the 

 other drainage of south-central Xew York was forced to southward es- 

 cape, mostly in tribute to the Susquehanna and through the new rock 

 gorge at Towanda, Pennsylvania. A late and probably rapid land up- 

 lift, rejuvenating the obsequent drainage, will probably be found to satis- 

 factorily account for the great depth and other anomalous features that 

 have been used as arguments for deep glacial erosion in Xew York. 

 Interglacial drainage may be important in this work. 



It will now be understood that when the earliest ice-sheet invaded Xew 

 York it found a topography unlike the present — a remarkable series of 

 parallel, deep, open, north-sloping valleys that headed southward, the 

 larger ones in Pennsylvania. The present divides in the valleys are due 

 to the moraine fillings left by the ice. The deep canyon-like valleys were 

 occupied by the glacier and some abrasion and smoothing of the walls 

 was inevitable. But it should not be forgotten that the ice-tonsrues in 



1 Bull. Geol. Soc. America, vol. 20, 1910, pp. 668-670. 



