J. W. SPENCER — THE IROQUOIS SHORE. 491 



ical glacial dams 400 miles to the northeastward, is in harmony with my views 

 previously set forth. The details in the present paper only locate the approximate 

 positions of the old shore as far northeastward as they have been definitely ex- 

 plored. Where the upward warping ceases or is replaced by a descending move- 

 ment toward the sea has not been discovered, so that it maybe found that the 

 Iroquois shore is lower in the region of Quebec than in the Adirondack region* This 

 idea of a lesser continental uplift in the northeast than farther southwestward has 

 already been hypothesized in one of my previous papers and subsequently pointed 

 out by Baron de Geer. 



That much drifting ice occurred in the northeastward extension of the [roquois 

 water is probable on account of its pitted shores, bowlder pavements and broken 

 features. It may be even possible that this body of water, which was at sea-level 

 was cut off from open water by local glaciers descending into the lower Saint Law- 

 rence valley, but these could not be sufficient to hold for ages a body of water 600 

 miles long and in part over 100 miles wide much above sea level. 



In Mr. Upham's paper on lakes Warren, Algonquin and Iroquois he has given 

 definitions differing from those of my original descriptions. 1 described lake 

 Warren as extending over the < Mitario basin as well as over the basins of the upper 

 lakes, for I know of terraces and other shore phenomena belonging to the eleva- 

 tion. The only systematic work on the Algonquin water was originally done by 

 myself and recently continued by Mr. Taylor, and I have shown that its level was 

 about 300 feet above the Iroquois plain. The dismemberment of the Warren water 

 was first pointed out by myself and, from the evidence, there appear to have been 

 many outlets — that at ( JhicagO being only one of them and not the outlet of a sep- 

 arate tdacial lake. 



Mi-. Gilbert's interpretation of the phenomena north of the Adirondacks as being 

 attributable to glacial lakes does not seem to me to be tenable, from the immense 

 amount of cumulative evidence set forth in this paper; but all the glacial charac- 

 teristics of the terraces and pitted plains may be easily explained by floating ice. 

 acting in the Laurentian archipelago upon the Iroquois shore; which would only 

 be located as above described even upon Mr. Upham's explanation of the closing 

 of the Ontario basin by a glacial dam at Quebec. 



CHANNELS OVEK DIVIDES NOT EVIDENCE PER SE <>F GLACIAL LAKES. 



BY .1. W. SPENCER. 



The locality of this paper was visited in company with Mr. < I. K. Gilbert, and 

 the descriptions given are only sufficient to allow a staternenl of ray views, as 1 

 consider it a very important region. 



The valley of Black river, New York, extends nearly 40 miles above Carthage, 

 forming an embaymenl on the northern Hanks of the Adirondack massif. Boon- 

 ville is on the divide between the head of this valley and an eastern branch of the 

 Mohawk river. The limestone fl 'of the divide is l.lll feet above the sea. From 



it the valley rapidly widens, and at a point ten miles to the south it is two miles 

 in width. At a shorl distance farther southward, the lolls rapidly fall away, leaving 



a comparatively low country. A few miles westward, the parallel [roquois beach 

 records differential elevation of the land amounting to four feet or more per mile. 

 In the greal valley of the I '-lack river, conspicuous terraces 3 occur north of Boonville 



