EDITORIALS. 625 



Tertiary and Quarternary Stream Erosion of North America, by 

 Warren Upham ; The Emergence of Springs, by T. C. Hopkins. 



As the writer was unable to hear a considerable number of these 

 papers his notes must be confined to comparatively' few of them. 

 The paper of Mr. Lincoln presented a very interesting sketch of 

 the quite remarkable evidences of glacial erosion and modifica- 

 tion of surface in the Finger Lake region of New York. He 

 showed, successfully we think, that the existing topography could 

 not have arisen in its present form through the agency of sub- 

 aerial degradation alone nor by the simple deposit of drift material 

 on a surface so produced, but that a very notable amount of 

 reshaping of the rock-surface was the result of glacial abrasion. 



Mr. Frank Leverett made a quite important contribution to 

 the data bearing upon the stages and duration of the earlier gla- 

 cial epoch. He has recently discovered evidence that the Rock 

 River formerly flowed nearly due south from a point near Rock- 

 ford into the Green River basin, and presumably onward to the 

 great bend of the Illinois River, near Hennepin, where an old 

 deep channel exists. From this course the river was diverted to 

 its present south-westerly course by the earliest or at least one of 

 the earlier stages of the ice invasion of that region. Between 

 the time of this diversion and the stage at which the kettle 

 moraine was formed across the Rock River about forty miles to 

 the north, near janesville, Wis., the river cut a trench in rock 

 across a succession of preglacial cols to maximum depths esti- 

 mated at 100 to 125 feet. Mr. Leverett made careful estimates 

 of the total amount of rock excavation and found it to amount 

 to one square mile 1100 feet deep. Stated in another form, this 

 equals a trench 100 feet deep, one mile wide and eleven miles 

 long, or one-half mile wide and twenty-two miles long. After 

 the trench had been cut, the glacial wash from the outer edge of 

 the kettle moraine partially filled the trench as shown by rem- 

 nants of terraces still existing at different points along it. The 

 amount of this filling within the area of the above computation is 

 estimated as one square mile 900 feet thick or T 9 r of the amount 

 of rock excavation. Since the formation of these gravels the 



