Geography of Ohio 231 



distance east of the Ohio-Pennsylvania state hne, the Whittlesej- 

 beach rises 150 feet.^- The Warren beach rises 42 feet between 

 the east border of Ohio and Westfield, N. Y., a distance of 50 to 

 55 miles. '^ In a distance of 60 miles between Rome and Adams 

 Center, N. Y., the Iroquois beach rises 235 feet.^* These old shore 

 lines do not show the same change in tilt; this fact suggests 

 that the differential movement was in progress, as the lakes suc- 

 ceeded one another. 



Land tilting in the St. Lawrence drainage basin is still in pro- 

 gress. Men have been watching it closely over half a centur}-. 

 It has been estimated that if the movement continues for 500 years, 

 the tilt will have become sufficient to cause the upper Great 

 Lakes to flow into the Mississippi valley by the old Chicago gla- 

 cial lake outlet. The course of this outlet is now followed by the 

 Chicago sewerage canal. This seems like a bold statement, but 

 a study of altitudes shows that the tilt need not be very great to 

 cause Lakes Michigan, Huron and Superior to flow southward past 

 Chicago. Should this diversion be brought about, there will be 

 very little water left to make a Niagara river. The fq.lls will then 

 cease to be of much importance. 



^- Leverett, Monograji/i X LI. V. 8. Cleol. Survey (1902), p. 75fi. 

 ^^Ibid., p. 765. 

 " Ibid., p. 774. 



