THE CHAMPLAIN SEA IN THE LAKE ONTARIO BASIN 547 



Near Ottawa the upper limit of marine submergence has recently 

 been determined 1 to be 690 feet above sea-level. At Belleville the 

 highest marine plane has an altitude of 323 feet. 2 If the gradient 

 is regular between those two localities, the altitude at Yarker would 

 be close to 440 feet. The nearest point on the shore line of Gilbert 

 Gulf in New York, where its features have been mapped by Fair- 

 child, is a small hill 4^ miles southwest from Clayton. 3 This hill 

 is 35 miles S. 70 E. from Yarker; the Gilbert shore encircles it at 

 an elevation slightly above 400 feet. The post-Champlain isobases 

 in this neighborhood run approximately east and west. It is, 

 therefore, quite clear that the Napanee Valley and adjacent uplands 

 were submerged beneath the waters of Gilbert Gulf at least as far 

 northward as Yarker (elevation 425 feet). 



That this submergence did not take place when the ice front 

 stood south of the divide at the head of Napanee Valley is 

 clearly indicated by the presence of a valley train of fluvio-glacial 

 gravels within the valley. Remnants of the gravel beds are pres- 

 ent at many localities between Yarker and Napanee. Between 

 Newburgh and Strathcona their nuvio-glacial, rather than glacio- 

 lacustrine or glacio-marine, origin is readily apparent. As indi- 

 cated in Fig. 4, the gravel train has a plane upper surface and its 

 remnants are now distinctly terrace-like. The summit of the 

 valley train is approximately 50 feet above the modern valley flat 

 and has a similar gradient, 8 or 10 feet to the mile. The gravels 

 and sands are irregularly bedded; cross-bedding is common, and 

 assortment according to size of pebbles is very incomplete. Many 

 of the stones are striated or faceted by glacial action. The valley 

 train is in every way a typical sub-aerial fluvio-glacial deposit similar 

 to the comparable outwash gravels of the Fox River Valleyin Illinois. 



The lowest and most southwesterly remnant of the Napanee 

 valley train is within the city limits of Napanee at an elevation of 



1 W. A. Johnston, "Late Pleistocene Oscillations of Sea-Level in the Ottawa 

 Valley," Canada Geol. Survey, Mus. Bull. 24, 1916, p. 5. 



2 F. B. Taylor, "Gilbert Gulf," U.S. Geol. Survey Mon. 53, 1915, pp. 445-46; 

 A. P. Coleman, "Marine and Freshwater Beaches of Ontario," Geol. Soc. Amer. Bull., 

 XII (1901), 129-46. 



3 H. L. Fairchild, "Pleistocene Features; Clayton-Lafargeville District," N.Y. 

 State Mus. Bull. 145, 1910, pi. 46. 



