IROQUOIS BEACH IN NEW YORK STATE 359 



into which the old shore is split up north of the Rome outlet with a 

 view to settling the question of the deformation of the shore during the 

 existence of lake Iroquois.* The portion of the Iroquois shore beyond 

 the province of Ontario given on the accompanying map is copied from 

 the one published by the New York state survey, which appears in the 

 main to be taken from Doctor Gilbert's earlier work. It is of special im- 

 portance as showing the old outlet of lake Iroquois past Rome, through 

 the Mohawk valley into the Hudson. From Lewiston to Rome the old 

 shore appears to be a unit, as it was found to be on the Ontario side as 

 far as Colborne, and its general characters seem to be much like those 

 described in former pages. A great bay opened southeastward with 

 many inlets and islands, a counterpart of the island-filled bay between 

 Trenton and Peterboro on the north side. Beyond the Rome outlet 

 toward the north the shore is broken up into two or more beaches, as 

 given in tabular form by Professor Fairchild, but he was unable to trace 

 continuous shorelines spreading more and more widely apart as one 

 advances north, and concluded that a shifting of water levels during the 

 existence of lake Iroquois is not yet proven. f He is more inclined to 

 think that the different levels of the gravel bars result from the lowering 

 of the Rome outlet and not from the tilting of the basin. Against this, 

 however, is the fact of the unity of the beach from the Rome outlet west 

 to Hamilton and northeast to Colborne. A lowering of the outlet should 

 have affected the whole shore, and not only the portion northeast of a 

 line between the Rome outlet and Colborne. 



On each side of lake Ontario we find this old shore split up into sepa- 

 rate beach levels toward the northeast. The separate beaches are very 

 distinctly marked up to points near Watertown in New York and Have- 

 lock in Ontario, but beyond these points the Iroquois shore can no 

 longer be traced with certainty. The first recognition of the splitting up 

 of the beach into several levels, both in New York and Ontario, to the 

 north of the outlet is due to Doctor Gilbert, who discovered the Rome 

 outlet and connected the divergence of the beaches with a tilting of the 

 basin during Iroquois times. 



Tilting of the Iroquois Beach 



That the Iroquois beach is no longer horizontal was proved long ago 

 by Doctor Spencer north of lake Ontario and Doctor Gilbert south of it. 

 The direction of uplift has generally been stated as north 27 degrees east, 

 but this does not accord with the facts north of lake Ontario, and in any 



♦Pleistocene Geol. Western New York, 1900; from Twentieth Rept. U. S. State Geologist. 

 t Ibid., p. rill. 



