260 W. UPHAM — GLACIAL LAKES IN CANADA. 



Gilbert finds a beach of this glacial lake 860 feet above the sea. Doubtless 

 a distinct series of these beaches is traceable upon the southwestern part of 

 Ontario from near Toronto and Hamilton westward and northward to Geor- 

 gian bay, marking pauses in the uplifting of the country while the ice-barrier 

 still occupied a large part of Lake Ontario and turned the glacial drainage 

 of this whole district into the Mississippi. 



The further stages of the glacial recession, uncovering an outlet from the 

 Lake Ontario basin by Rome to the Mohawk and Hudson, and the history 

 of the Niagara river and of the glacial Lake Ontario, have been ably dis- 

 cussed by Gilbert. On a diiferent theory, not recognizing an ice-sheet and 

 referring the high ancient beaches of this basin to marine submergence, the 

 same field has also been elaborately and ably studied by Spencer. Ac- 

 cording to the glacial theory held by Gilbert, which seems to me the true one, 

 while the retiring ice-sheet still rested against the Adirondack mountains 

 and thence stretched across the St. Lawrence valley to the Laureutide high- 

 lands north of Montreal and Quebec, the glacial Lake Ontario, outflowing 

 at Rome, formed a well marked beach which Gilbert has mapped, with de- 

 terminations of its height by levelling, from the Niagara river east to Rome 

 and north to the vicinity of Watertown. The Canadian portion of this beach, 

 surrounding the western end of Lake Ontario and running along its northern 

 side to the vicinity of Belleville, has been similarly traced by Spencer, who 

 has given to the beach and lake the names " Iroquois beach " and " Lake 

 Iroquois." The height of Lake Ontario is 247 feet ; and that of the old 

 outlet crossing the water-shed at Rome is 440 feet, above the sea level. 

 Thence the beach in its course northward adjacent to the eastern end of Lake 

 Ontario has a gradual ascent of about five feet per mile along- a distance of 55 

 miles northward to the latitude of Watertown, where the highest beach is 730 

 feet above the sea, showing that a differential uplift of about 290 feet has 

 taken place, in comparison with the Rome outlet. From Rome westward to 

 Rochester, the beach has nearly the same height with the outlet ; but farther 

 westward it descends to 385 feet above the sea at Lewiston and 363 feet at 

 Hamilton, at the western end of Lake Ontario. Continuing along the beach 

 north of the lake, the same elevation with the Rome outlet is reached near 

 Toronto, and thence east-northeastward an uplift is found, similar to that 

 before noted east of the lake, its amount near Trenton and Belleville above 

 Rome being about 240 feet. 



Only two surfaces of former levels, which are supplied by the old shores of 

 Lakes Warren and Iroquois, conduct us from Chicago to Watertown and the 

 mouth of Lake Ontario. Between the level of Lake Warren at the eastern 

 end of Lake Erie and the latest level and highest beach of Lake Iroquois at 

 the western end of Lake Ontario, there is a vertical fall of approximately 500 

 feet ; and from the latest in the series of several Iroquois beaches near Water- 



