PLEISTOCENE MARINE SUBMERGENCE 21 



The difference in time between the stages shown in plates i and 

 2 is relatively small, and no attexnpt is made to show the slightly- 

 greater constriction of the valley waters in the Hudson during the 

 second stage. 



Plate 3. This map does not sihow the geoigrapihy at any 

 moment of time, but the greatest submergence and widest extent of 

 the sea-level waters in all districts, as indicated by the summit shore 

 features. The land uplift as a progressive "wave, moving north- 

 ward, produced constant reduction of the estuary on the south, 

 while near the ice front the land was at, or near, its greatest depres- 

 sion and the waters at their maximum extent. This is illustrated 

 in plates i and 2. 



The amount of marine submergence and postglacial uplift is 

 shown approximately by the lines of equal uplift, or isobases. 



Plate 4. This map is intended to show the locations of the 

 shore lines in the northern part of the State, east, north and west 

 of the Adirondack highland. 



In the Champlain valley only the sea-level waters, the marine 

 inlet, existed, but in the St Lawrence valley the glacial Lake Iroquois 

 preceded the ocean-level waters. The vertical interval between the 

 Iroquois and the marine planes is 290 feet (see plate 11). The 

 marine plane passes under Lake Ontario at the south edge of the 

 area here shown, or approaching Oswego. The rise of the land, 

 over 500 feet, at the head of the St Lawrence (plate 9) has lifted 

 the surface of Lake Ontario to 246 feet above the sea, and buried 

 the southwest shore of the sea-level waters (Gilbert gulf), where 

 the land uplift was less. 



Plate 5. We have in this map the shore phenomena plotted on 

 the topographic sheets. The legend and notes make the map quite 

 self-explanatory. Plate 6 joins the west edge of plate 5, and plate 

 8 joins the south edge. 



In his map of the Mooers sheet Woodworth indicates many 

 fragments of beaches which are not here shown (81, with map). 

 However, the lower shore features do not involve any important 

 element in the history, as such are to be expected, under favoring 

 conditions, at all inferior levels. Weak bars occur irregularly at 

 points where the several factors favoring their construction were 

 present in sufficient degree. 



The lower bars in this map belong mostly to the Franklin Center- 

 Stockwell-Covey Hill post office .shore Hne. This shore with its 

 great series of strong cobble beaches represents a level 215 feet 

 beneath the summit plane, and possibly records an episode of some- 



