668 PROCEEDINGS OF THE BALTIMORE MEETING 



The discussion on this paper was participated in by B. K. Emerson, 

 W. S. Barley. F. D. Adams, and E. S. Bastin. 

 After this the following paper was read by title: 



PETROLOGY OF THE SOUTH CAROLINA GRANITES [QUARTZ MONZONITES) 



BY THOMAS LEOXABD WATSON 



The next two papers, being on related topics, were presented orally in 

 succession : 



TERTIARY DRAIXAGE PROBLEMS OF EASTERN XORTH AMERICA 

 •BY AMADEUS W. GRABAU 



[Abstract] 



The Laurentian river of Spencer carried the collected drainage of the Great 

 lakes through Ontario valley and out by the way of the present Saint Law- 

 rence. The Finger Lake valleys and the Genesee are regarded as made by 

 tributary northward flowing streams. Fairchild regards these as northward 

 flowing tributaries of a i possibly I westward flowing river in the Ontario 

 valley. The author has in the past shown that a normal sequential drainage 

 system, the general direction of which was northward, and in which the minor 

 streams were beheaded by the master, accounted for all the topographic fea- 

 tures of the region in question. Subsequent blocking of some of the channels 

 by drift and deepening of others by ice. and a general depression of the country 

 to the northeast, has produced the present drainage system. The problems 

 were discussed in the light of accumulated facts. 



DRAINAGE EVOLUTION IN CENTRAL NEW YORK 



BY H. L. FAIBCHILD 



[Abstract] 



The paper aims to assist in the elucidation of the complex physiography of 

 the western hell of New York state. Three maps represent graphically the 

 general evolution of the drainage and the interference by glacier invasion of 

 the normal stream development. 



The first map shows the existing valleys which are. apparently, an inher- 

 itance from the ancient drainage, southwestward. across the uplifted pene- 

 plain. These inherited valleys fall into three classes : i a I those in which the 

 present flow is the same as the primitive. < ~b i those which are abandoned or 

 left as "hanging" valleys, and I c I those in which the stream flow has been 

 reversed. A remarkable parallelism is exhibited by these valleys, which. 

 except in the district of the Delaware and upper Susquehanna, are transverse 

 to the present master streams. At Lanesboro the primitive Susquehanna con- 

 tinued directly south, instead of bending northwest as now. and then occupied 

 in Pennsylvania the Tunkhannock valley. Other valleys in northern Pennsyl- 

 vania represent the continuation of the southwestward flow in central New 

 York. 



