188 PROCEEDINGS <>F COLUMBUS MEETING. 



In connection with the above the two following papers were read : 



THE IROQUOIS SHORE NORTH OF THE ADIRONDACK^. 

 BY J. \W SPENCER. 



In previous papers on the Iroquois shores of the Ontario basin, their position was 

 definitely located only to a point near Belleville, on the northern side of lake 

 Ontario. But, from the general character of the country. 1 pointed out the 

 necessity of extending the Iroquois water across a broad expanse of country to the 

 highlands north of the Ottawa river, cm the flanks of which shore deposits are 

 known at various localities. I have also shown that the Iroquois water stood at < li- 

 near sea-level ; and in my working hypothesis considered the Iroquois water as an 

 extension of the gulf of Saint Lawrence into the Ontario basin, although more or 

 less obstructed by ice. Sinee the last paper was written, Mr. O. K. Gilbert and 

 myself have revisited the region as far as a point 100 miles northeast of Water- 

 town. ( >wing to Mr. Warren TJpham's recent acceptance of the extension of the 

 open Iroquois water as far as Quebec, it becomes desirable that the old shore line, 

 so far as definitely surveyed, should be published. 



• After a long stretch of unbroken continuity, the Iroquois beach is abruptly inter- 

 rupted by rocky cliffs on the side of the escarpment about ■"> miles east of Water- 

 town. Beyond this point, owing to the broken continuity, the remnants of the 

 ancient shore are more or less fragmentary. The old subaqueous plain extends up 

 the broad Black river valley far above Carthage, with gravel deposit- characterizing 

 portions of its margin. The northeastward elevation of the Iroquois beach in this 

 region rises at from five to six feet per mile. Beyond Carthage, the country becomes 

 more broken, being traversed by ridges of crystalline rocks, forming a late exten- 

 sion of the archipelago of the Thousand islands at a higher level. The drift de- 

 posits become more sandy, with very little clay, and consequently are less favorable 

 for the production of well defined beaches. The island character of this region is 

 particularly unfavorable for the development of well defined shore markings. But 

 wherever valleys enter the archipelago, their outlets are characterized by delta 

 deposits or terraces, whose hypsometric position can be predicted in proceeding 

 eastward. 



At Mr. Frank Wilson's, 4 miles east of Watertown, the unquestioned beach is 

 broken into ridgelets between 730 and 704 feet, with a frontal gravel-bearing ter- 

 race at 682 feet. Below this horizon there is an extensive terrace plain east of 

 Watertown at about 535 feet. At the mouth of Indian river, at Natural bridge, 

 these delta deposits form terraces, with more or less beach structure, at an eleva- 

 tion between 829 and 802 feet, with a frontal -ravel plain descending from 7S7 

 feet downward. In both cases, the waves, in carving out the Lower terraces, have 

 removed portions of the higher ridgelets. Between these limits there is no strongly 

 marked terrace, hut the lower i- more confined to this regional topography than the 

 upper; ami where gravelly, the pebbles are subordinate to the sand. For quantity 

 and size of water-worn pebbles, the gravel deposits at Natural Bridge are physically 

 the equivalents of those of the Iroquois beach to the southwestward. Above and 

 below this level, at Natural Bridge, there are no fragments of ancient water lines 

 liable to be mistaken for the Iroquois level. The elevation of these deposits is that 

 which would he expected from the measured warping recorded about Watertown. 



