I'.M PROCEEDINGS OF COLUMBUS MEETING. 



which can be regarded as diagnostic. Some of the lower terraces south of the 

 col — those indicated by the anemid asat 970 and 940 feel above tid( — have peculiar 

 features indicating that they are not Littoral. Though restingon a steep slope, they 

 are characterized by well rounded bowlders of large size, from one to three feet in 

 diameter, ruder wave action such material would he rolled down the slope. 

 Moreover, each of these terraces is margined toward the valley by a parapet of the 

 same material. The parapet is low, not more than one or two feet bigh, but it 

 suffices to control the drainage of the terraces. These features suggest that an ice 

 tongue once occupied the bottom of the valley, and that a torrent coursed between 

 the ice margin and the valley wall. Our brief visit afforded no time to test this 

 explanation and I do not offer it with confidence ; but its suggestion will illustrate 

 to the Society the danger of the assumption that all high lying terraces record levels 

 of standing water. 



Mr. 1. C. Russell remarked : 



Recently it has been my fortune to observe in association with Alaskan glaciers 

 certain terraces with marginal parapets which were formed in the manner suggested 

 by .Mr. Gilbert, i. e., by streams following the lateral edges of glaciers. 



Dr. Spencer replied : 



1 have shown in my various papers preceding this that the deformation which 

 lifted the beaches in the lake region was principally produced after the Iroquois 

 episode, and that the 350 to 400 feet of eastward elevation between the head of lake 

 Michigan and the eastern end of lake Erie affected the whole Iroquois plain and 

 lifted the old shore line at the head of lake Ontario to 86.'! feet above the sea, as 

 we see it to-day. Hence it seems to me to lie a defiance of observations to regard 

 the Iroquois shore as having been formed above sea-level, as has been also frequently 

 stated by Mr.TJpham, although Mr. Upham now extends the Iroquois water to the 

 vicinity of Quebec. 



That the region north of the Adirondacks may have been a sea filled with ice- 

 bergs or even a glacier is not considered here, but only that the Iroquois water-plain 

 continued at least 100 miles northeast of Watertown — a theory supported through- 

 out this very broken region (a former archipelago) by delta and terrace deposits at 

 the mouth of every river at elevations corresponding to the deformation measured 

 in the vicinity of Watertown. In composition and physical structure the appear- 

 ance is close, there being no other deposits liable to misidentification. Throughout 

 this region there are other than the delta and terrace deposits at the mouths of all 

 the old valleys corresponding to the Iroquois plain ; hut even though such deposits 

 may be christened "kames" and "pitted plains" by glacialists, their uniform 

 glacial origin has not been so demonstrated by actual connection with modern 

 glaciers that their occurrence is ex cathedra evidence of glacial dams. It is not 

 doubtfully located deposits upon which I based my criteria, but the recurring delta 

 and terrace deposits at the river mouths; hence the grounds which make my dis- 

 tinguished critic and myself " differ radically as to the criteria by winch shore ridges 

 and shore terraces are distinguished " from glacial levels; nor can 1 gerrymander 

 glaciers into the region to account for the chains of phenomena which are regarded 

 as characteristic of the Iroquois water-level ; hut it is unsafe to theoretically throw 

 glacial dams across beach deposits. 



