IROQUOIS ISOBASE 248 



. Feet 



Quays Siding 55'7 Coleman. 



Colborne 602* Spencer. 



Trenton 632* . Coleman. 



Queenstown 385* Spencer. 



Albion 430 Fairchild. 



Rochester 440 Fairchild. 



Sodus 456 Fairchild. 



Auburn 411 Fairchild. 



Canastota 441 Gilbert. 



Rome 460 Fairchild. 



Cleveland 484 Gilbert. 



Constantia 489 Gilbert. 



Richland 566 Fairchild. 



Adams 640 Fairchild. 



Adams Center 657 Gilbert. 



Brookside Cemetery 700 Fairchild. 



Farrs (east of Watertown) 733 Fairchild. 



* These are wye-level measurements. 



These measurements have been plotted at the respective localities on 

 plate 5, and isobases have been drawn across Lake Ontario with reference 

 to them. It will be noticed that the altitude of the Iroquois beach at York 

 (442 feet) is nearly equal to that at Eochester (440 feet) and that at 

 Canastota (441 feet). The isobase drawn nearly through these locali- 

 ties, therefore, serves to fix the probable direction of tilt at that altitude. 

 It indicates what Fairchild and other writers have remarked, that the 

 direction of tilt is more nearly due southward over the east end of Lake 

 Ontario than over the west end. The same feature is met also in draw- 

 ing isobases from Quays Siding (557 feet) to Eichland (566 feet) and 

 from Trenton (632 feet) to Adams (640 feet). 



Coleman found that the direction of inclination of the Iroquois plane 

 over the western part of Lake Ontario is about south 20 degrees west.^^ 

 The isobases on plate 5 agree closely with his statement, running about 

 22 degrees south of east. 



Comparison of the Two Water-planes 



A comparison of the Iroquois isobases with the Algonquin isobases in 

 southwestern Ontario brings out remarkable similarities of attitude in 

 the two planes. The direction of tilt, as we have seen, is within one or 

 two degrees of south 20 degrees west in both cases. This obviously 

 means that the two beaches have been deformed by the same set of move- 

 ments. 



Coleman : op. cit., p. 360. 



