1881.J ^^^ [Lesley. 



And so of each vallej' and each mountain successively as one follows 

 the terminal moraine north-westward, across the gorge of the Lehigh, 

 across Hellkitchen mountain, across Conyngham valley, across the 

 Nescopee mountain, across the Susquehanna above Berwick, across the 

 Schickshinny mountain, near its west end, across the Muncy hills, across 

 the Alleghany mountain north-east of Williamsport, across the Loyalsock 

 ravine, and the Canon of Lj'coming creek, the plateau of Potter county, 

 to its great angle north of Olean and Salamanca in New York. 



Along this whole line, the topography to the east (under the ice) is 

 precisely the same as the topography to the west (where ice has never 

 been) and the only distinction observable is this : that west of the great 

 moraine there is no drift and no lakes ; east of the moraine the whole 

 surface is sheeted with drift and spotted with ponds ; — and all the scratches 

 point south-south-westward, the ice evidently having moved from the 

 Adirondacks. 



From Salamanca the Terminal moraine has been traced by Mr. Lewis 

 and Mr. Wright as a nearly straight ridge of trash, south-westward, across 

 Western Pennsj^lvania to the Ohio line (near Darlington) 13 miles north 

 of the Ohio river ; the scratches all pointing S. S. E. and S. as if coming 

 square across Lake Erie and ascending the highlands to the south of it, 

 Nowhere along this line has it affected the topography ; it has merely de- 

 posited drift, and choked the ancient valleys so as to reverse the drain- 

 age. Mr. Carll has pointed out the noses of hill-spurs which he thinks 

 were sharpened by the ice ; but even this slight modification of the pre- 

 existing topography, occurs at places lying outside or to the south of the 

 terminal moraine, and we must therefore find some other explanation 

 for it. 



It seems unreasonable in the highest degree therefore to speak of the 

 glacial erosion of Lake Erie and Lake Ontario, when it is evident that the 

 ice sheet was perfectly incompetent to erode the countries which it in- 

 vaded, and left them everywhere precisely in the topographical condition 

 in which it found them ; merely scratching their rock exposures, incumber- 

 ing and embarassing somewhat their lines of drainage, spreading a slight 

 sheet of drift material over them, and tearing a few blocks out of the looser 

 outcrops and depositing these blocks after a short transit ; often on higher 

 levels, and sometimes on much higher levels ; for Mr. Lewis has found 

 Helderburg blocks carried completely to the top of the Kittatinny moun- 

 tain. 



