64 Tin American Geologist. July, 1894 
teorological explanation ;is follows: The melting of the vasl western 
pari <»r the ice-shee1 in the United States, from North Dakota and Min- 
nesota east t<> the lake Erie basin, would supply t<> our eastwardly 
moving storms a very great amount of moisture to be precipitated 
farther east. Thai precipitation 1 think to have been mainly snow as 
these storms, moisture-laden from the western ice-melting, sweptover 
the more eastern pari of the ice-sheet. Hence, the eastern great ice- 
lobe from Salamanca to I g Island. Cape Cod. and the Gulf of Maine 
would be fed and fattened to be thick and spread in some places even 
beyond its previous limits, while all of the ice-sheet farther west in the 
United States was being melted away. 
Another unforeseen conclusion, relative to the volume of the Niagara 
river while the ice-sheet was departing, is brought by our consideration 
of the uplift of the northern side of the glacial lake Warren, which 
along its extent of 600 miles from west to east was rapidly raised in 
genera] about 350 feet, as compared with the Chicago outlet, before the 
date of the Nipissing beach. This I think to be the first shore line 
formed in that northern area after the Chicago outlet ceased and after 
lake Warren was thereby succeeded by lake Algonquin in the basins of 
Michigan, Huron and Superior, while lake Iroquois then began to exist 
in the Ontario basin, outflowing by Rome, N. V.. to the Mohawk and 
Hudson. But this Nipissing beach, at the present lake level at Duluth, 
25 feet above lake Superior at Houghton and Marquette, and 50 feel at 
theSault Ste. Marie, rising to 110 feet above lake Superior or 743 feet 
above the sea at lake Nipissing. is so high, 50 feet upon a width of more 
than a mile, above the watershed east of that lake leading to the Mat- 
lawa ami Ottawa rivers, that I cannot believe a river of such depth and 
width to have there outflowed. Instead. I believe that the ice-sheet then 
still remained as a barrier upon the Mattawa and Ottawa areas: and 
careful study of Prof. .1. W. Spencer's maps in recent volumes of the 
Am. .lour, of Science (Dec. 1890; Jan. and March, 1891; March. 1894; 
also Bulletin, G. S. A., vol. n. pp. 465-476, April, 1801) of the Huron and 
Erie shore lines convinces me that the outflow of lake Algonquin at the 
time of the Nipissing beach went by way of the presenl St. Clair and 
Detroit rivers and along the bed of lake Erie to the incipient Niagara 
and lake Iroquois. Seven-eighths of all the uplifting of the Nipissing 
area which carried its watershed above the bight at which it could be 
an outlet of lake Algonquin had taken place before the Niagara river 
and lake Iroquois began to exist. Later, while yet the ice was a barrier 
on the Mattawa area. I believe that tin' continuation of that uplift full}' 
raised the Nipissing-Mattawa divide above lake Algonquin, for mean- 
while the lake Iroquois area was undergoing a large differential uplift 
of increasing amount from south to north. The Niagara river thus ap- 
pears to have had a volume equal to the present during its entire his- 
tory. If there was any time of diversion of the waters of the upper 
Laurentian lakes to the Mattawa valley, it was of very brief duration, 
and would require only an insignificant addition to the estimate of 7,000 
years for the dura I ion of t he Niagara river and of the Postglacial period. 
