504 G. H. CHADWICK GLACIAL LAKE PROBLEMS 



migrating bulge. That it had no free communication with salt water 

 via the Hudson Valley is an inevitable corollary of Fairchild's discussion 

 of the Eound Lake region.^* Analysis of that paper shows that long 

 before the unblocking of the north end of the Adirondacks, while still 

 Lake Iroquois was discharging through the Mohawk and cutting the 

 Eound Lake channel, the Hudson Y alley at that point had lifted so far 

 as to confine the Hudson River to the narrow trench it was reexcavating 

 in the clays of the Lake Albany filling. Lake Albany was gone. There 

 was no open strait of salt water (or any other water) from New York to 

 Plattsburg, but a river of fresh water flowing (with a gradient) south- 

 ward and holding Lake Vermont to superoceanic level. The true marine 

 waters (Hochelagan Sea) entered the Champlain A^alley only when ad- 

 mitted from the northeast, past Quebec. By the original definition 

 "Gilbert Gulf" is the portion of these marine (tidelevel) waters confined 

 to the Ontario Basin, and the name should not be extended over the 

 region in which Woodworth's "Hochelagan Sea" has clear priority.^^ 



The Vermont beaches are finely developed at 740 feet above tide and 

 doT\Ti, both around Covey Hill and far into the Ontario-Saint Lawrence 

 Valley. The true marine beaches are those originally recognized as such 

 from 523 feet above tide down, on Covey Hill. Between these two sets 

 is a gap of nearly 100 feet, marking the elevation of Vermont waters 

 above sealevel just prior to their extinction. 



Above the Vermont beaches, between them and Iroquois, in the 

 Ontario-Saint Lawrence Valley, lie the "Emmons" beaches of Fairchild, 

 rediscovered and renamed "Frontenac'' by Taylor.^^ 



The Algo]^quix Lakes 



However intricately interwoven may be the Algonquin beaches, in 

 point of historical sequence there are several distinct water bodies at 

 present passing under the name "Lake Algonquin." Leverett and Taylor 

 discriminate (1) an "early Lake Algonquin" confined to the south end 

 of the Huron basin, with Detroit (that is. Port Huron) outlet; (2) 

 doubtfully a tripartite lake with outflow divided past Detroit and Chi- 

 cago, which seems to be an expanded Lake Chicago; (3) the true Algon- 

 quin, tripartite, with Trent River escape, and (4) the second Algonquin, 

 restored to Port Huron outlet. To avoid confusion of speech, it is sug- 

 gested that the first stage be called rather the primitive Huron, and tliat 



"Bull. 195. N. Y. State Museum, pp. 12-15. and map pi.: compare also Bull. 215-6. 

 N. Y. State Museum, pp. 28, 40, ligs. 10. 11 : Bull. 154, X. Y. State Museum, pp. 30-3. 

 fig. 5 : Bull. Geol. Soc. Amer., vol. 33, p. 525. 



" Bull. 84, N. Y. State Museum, p. 220. 



16 Bull. 158, N. Y. State Museum, p. 34 ; Bull. 164. X. Y. State Museum, p. 22 : Mon. 

 LIII, U. S. Geol. Survey, pp. 32.5. 445 ; Proc. Roch. Acad. Sol., vol. 5. p. 138. 



