362 A. P. COLEMAN — IROQUOIS BEACH IN ONTARIO 



The inclination of the highest beach is still less satisfactory, working 

 out at 7.22 feet per mile between Quays and Trenton and only 5.3 for 

 the island north of Campbellford, according to my figures, though Doc- 

 tor Gilbert's separation of the highest from the lowest beach by 90 feet 

 gives an inclination of 6.8 per mile. The West Huntingdon island does 

 not reach the higher water levels, and so is unavailable for our present 

 purpose. 



From the figures given above it will be seen that the rate of diverg- 

 ence of the highest from the lowest beach is not very uniform, though 

 in general the spreading apart, with increased distance from the starting- 

 point, is clearly indicated. At Silver lake, 9 miles from Quays, it is 28 

 feet, or 3 feet per mile. At Trenton, 18 miles away (in the direction 

 north 20 degrees east), it is 55 feet for the two best denned levels, or 3 

 feet per mile. On the island north of Campbellford, at 31 miles, it is 

 only 43 feet by my determinations, but 90 feet by Doctor Gilbert's, the 

 latter giving nearly 3 feet per mile. 



Relation of the Iroquois Beach to the Rome Outlet 



Doctor Gilbert showed long ago that a river channel drained lake 

 Iroquois through the Mohawk valley toward the Hudson, and drew the 

 inference that if the tilting of the region was in progress during the ex- 

 istence of lake Iroquois, its effects should be recorded in the beaches. 

 The splitting up of the gravel bars to the northeast he looked on as evi- 

 dence in favor of this conclusion, and he expected that proofs of lower 

 water levels than the last one would be found near Hamilton, at the 

 opposite end of the lake. Doctor Spencer, on the other hand, believed 

 that the Rome outlet was of little importance, and that the "Iroquois 

 water," as he preferred to call it, was an arm of the sea, an extension of 

 the gulf of Saint Lawrence; perhaps freshened, however, by the rivers 

 flowing into it, as some of the great Siberian rivers are stated to freshen 

 the gulfs into which they flow. 



If the Iroquois water was connected with the sea — that is, stood at 

 sealevel — and the proved elevation toward the northeast was unaccom- 

 panied by a depression toward the southwest, and there is no known 

 evidence of such a depression, the effect of the differential elevation of 

 the region during the lifetime of the " water " would be to form a series 

 of continuous beaches running the whole length of the shore, but spread- 

 ing farther and farther apart toward the center of most rapid elevation 

 to the northeast. There could be no crossing of the highest and lowest 

 beaches. 



In earlier parts of this paper evidence has been given of the existence 



