712 PROCEEDINGS OE THE OTTAWA MEETING 



during 1903 and 1904; the faunas determined and the geological horizons to 

 which they are referable, together with correlations of results in previous ex- 

 plorations. The paper is illustrated with specimens from Beechy island, Lan- 

 caster sound, and other localities. 



The following paper was read, in absence of the author, by J . F. Kemp : 



TYPES OF SEDIMENTARY OVERLAP 

 EY A. W. GRABATJ 



Eemarks were made by H. M. Ami and C. W. Hayes. The paper is 

 printed as pages 567-636 of this volume. 



The next paper was 



GILBERT GULF (MARINE WATERS IN ONTARIO BASIN)* 

 BY H. L. FAIRCHILD 



That all the shorelines of the extinct glacial lakes in the Laurentian basin 

 have now an upward slant in northward directions is a well known fact of 

 observation. Another long recognized fact is the occurrence of marine deposits 

 of Pleistocene age in the Champlain and Ottawa valleys, a whale skeleton being 

 found as far inland as Welchs siding (near Smiths Falls), some 30 miles north- 

 west of Ogdensburg. If the tilt is due to northward uplift and not to south- 

 ward downthrow, it follows that the altitude of the land surface at any point 

 was, during the life of those lakes, as much below the present height as the 

 amount of differential uplift. From the above facts and principle it has long 

 been recognized that the carrying down of the deformed planes of the ancient 

 lakes to horizontality would carry the head of the Saint Lawrence valley far 

 below sealevel. The conclusion follows that when the Labradorian ice-sheet 

 melted away from the upper Saint Lawrence valley the sealevel waters spread 

 westward through the straits at the Thousand islands and occupied the Ontario 

 basin ; and the studies of Gilbert, Coleman, Spencer, Taylor, and others seem to 

 have made the theoretical conclusion a certainty. 



The sequence of events would seem to have been as follows : While the ice- 

 body was blocking the upper Saint Lawrence valley the waters in the Ontario 

 basin were held up to the level of Rome and forced to outflow to the Mohawk- 

 Hudson; but when the ice waned on the north slope of the Adirondacks and 

 opened passes lower in altitude than the Rome outlet, the Ontario waters (lake 

 Iroquois) were diverted to the northern escape and flowed out to the Champlain 

 valley. The rivers draining the sub-Iroquois waters must have washed the 

 ice-front, and must have shifted their position to lower and lower levels as the 

 ice-front backed away on the north-facing slope. The existence of such ice- 

 border or proglacial river channels on the north and northeast flanks of the 

 Adirondack massif was determined by Doctor Gilbert some years ago, and the 



* By permission of the New York State Geologist. 



