90 PEOCEEDIXGS OF THE BALTIMORE MEETING 



at various localities facing the open sea. thus ruling out the idea of glacial 

 waters. 



The paper will give precise location and description of the marine features 

 over the area in question. 



Eead by title by request of the author. 



TOPOaRAPHIC FEATURES OF TEE HUD SOX VALLEY AXD TEE QUESTION OF 

 POST-GLACIAL AIARIXE WATERS IX TEE EUDSOX-CEAMPLAIX VALLEY 



BY JAMES H. STOLLEE 



iAij.^tract) 



The subsidence of the body of waters (Lake Albany i which occupied the 

 middle Hudson Valley following the retreat of the ice-front antedated the 

 opening of the Saint Lawrence outlet of the interior glacial lakes. The evi- 

 dence of this Is the occurrence of erosion terraces in the Lake Albany deposits 

 on either side of the Hudson River at Mechanicsville. The location, elevation, 

 and trend of margins of these terraces show that they resulted from erosion 

 by a western tributary river discharging into southward-flowing Hudson waters 

 at Mechanicsville. It has been shown that this tributary was the Iroquois- 

 Mohawk River. Other topographical evidence shows that the waters of the 

 Hudson Valley, after their subsidence to the levels indicated by the erosion 

 terraces, did not again rise to a higher level. The deductions from these facts 

 of topography are opposed to the conception of a body of marine waters con- 

 necting the Saint Lawrence arm of the sea with the ocean at Xew York. 



Presented extemporaneously by the author. 



DlSCE'SSIOX 



Prof. H. L. Faibchild: The map which I now exhibit C published as plate 10 

 in volume 27 of the Bulletin of this Society i shows the full amount of the 

 marine submergence of the Hudson-Champlain ^'alley. The upraised marine 

 plane now rises from zero south of Xew York City to at least 740 feet on the 

 international boundary, at Covey Hill. ( The details of the shore features in 

 this valley are awaiting publication as a bulletin of the Xew York State 

 Museum.) 



The rise of the land following the removal of the ice-sheet was by a wave 

 movement, and at the time of the late.st flow of the Iromohawk River, in the 

 Saratoga-Round Lake region, the locality had risen 175 feet : but it was yet 

 200 feet lower than it is now. It is quite possible that the Hudson Valley in 

 the region of Xew York City had then received its full amount of uplift, but 

 the Covey Hill district was then at its maximum depression. Even after the 

 extinction of Lake Iroquois the Covey Hill district was 740 feet lower than 

 at present. 



The erosion features in the Mechanicsville district, described by Professor 

 Stoller, were made by stream-flow— first, by the Iromohawk. down to the 20<:)- 

 foot plane : second, by the southward flow of all the Laurentian waters while 

 the glacier front rested against the highland of Maine and Xew Brunswick: 

 and, third, by the present Hudson and Anthony Kill. These features of stream- 



