SPLITTING OF BEACHES 247 



question. It is predicted that some splitting of bars, increasing north- 

 ward, will be found. Between AYatertown and Mai one precise data have 

 not been sought, but about 12 miles south of Canton, near Russell, Pro- 

 fessor Chadwick and the writer measured with aneroid a strong set of 

 Iroquois bars having a vertical range of at least 35 feet. 



The figures for Canadian points, from Professor Coleman, show that 

 the glacial uplift declines northward, and the vertical range of bars, as 

 measured in the field, has remarkable agreement with the theoretic derived 

 figures. The Iroquois altitude for West Huntingdon is probably too high. 



It should be noted, as an illustration of the wave uplift, that during 

 Glacial time Rome was lifted 111 feet more than Parrs, but that during 

 post-Iroquois time Parrs rose 211 feet more than Rome. This gives 

 Parrs a net excess of 100 feet, the difference shown by the isobases. 



In summarizing this topic, it may be said that south of the Rome or 

 fulcral line all the beach phenomena seem to be an effect of rising water ; 

 that the splitting of beaches north of the fulcral line declines in amount 

 or vertical range both north and south of Watertown; that the tabulated 

 figures for Canadian points show similar relation, and that .the splitting 

 is clue to later local land uplift, which probably occurred while the lake 

 outlet was at Covey Pass. This topic is further discussed below. 



Flooding of the south Shore of Iroquois 



The southern shore of Lake Iroquois has the characters which are pro- 

 duced by a rising water level. The rise of the lake surface was evidently 

 caused by the excessive lifting or differential uplift of the outlet at Rome. 

 Probably the most striking feature produced by the rising water is the 

 huge gravel bar at Hamilton, Ontario. This has been described by Cole- 

 man (95, pages 351-352), who implies that the flooding was toward 100 

 feet. Turning to our table, we find that while Rome was lifted 180 feet, 

 Hamilton was raised only 98 feet, and that consequently that point must 

 have been flooded 82 feet. It is more than mere singular coincidence that 

 83 feet is the depth in the Hamilton bar at which "unworn Mammoth 

 remains" (95, page 352) were found. 



By similar calculation the amount of flooding may be determined at 

 all points. It is estimated that the flooding in the Rochester district was 

 about 70 feet and at Syracuse 45 feet. 



To determine the altitude of the initial water surface at any point on 

 the south-shore beaches, we deduct the amount of flooding, plus the 

 amount of total uplift, from the present height of that point. For ex- 

 ample, at Hamilton the total uplift, as figured from the isobases of the 

 map, is 170 feet; the flooding is 82 feet. The sum of these deducted 



