MIDDLE PALEOZOIC SEDIMENTATION. 43 



This Northeast Bay must have received the embryo Hudson, a stream then 

 of little length but of abundant Adirondack waters ; and also such other 

 streams as the slopes and rains could produce; but no salt-water currents nor 

 tides bearing sand and gravel from Canada and the Atlantic borders on the 

 northeast. Aud even in the Lower Helderberg period, when it is supposed 

 (first by Logan) that the broad Champlain Lake region was again under 

 salt-water, there were no contributions of coarse sediment from the Canada 

 and Labrador region, although there must have been of living species, for 

 the Lower Helderberg rocks over the region are limestones, and mostly 

 argillaceous limestones. An opportunity for such fragmental contributions 

 by these Champlain Straits may have existed in the epoch of the Cauda 

 Galli grit, at the commencement of the Devonian, as suggested by the 

 presence of its beds, according to Prof. Wm. M. Davis, over the lower 

 Helderberg in Becraft's Mountain, east of the Hudson river ; but this is 

 not probable. 



I would add that the closing of the Lake Champlain area against the sea 

 cotemporaneously with the emergence of the Green Mountains, and its con- 

 tinuing to be essentially closed, signifies that the region of the Appalachian 

 subsidence no longer embraced the Green Mountain and Lake Champlain 

 area, although it continued to extend over much of the eastern half of New 

 York, as we learn from the many thousand of feet in thickness of the later 

 Upper Silurian and Devonian formations. 



Observe here what a blow the fact of this closed Northeast Bay gives the 

 old theory — which I have held as well as others — that the coarse and fine 

 sediment for Appalachian rock-making, during the Upper Silurian era and 

 afterwards, came in, period after period, from the northeast, through Labra- 

 dor currents. The facts from the distribution of New York and Canadian 

 Devonian and Carboniferous rocks bring us to the unavoidable conclusion 

 that all the sedimentary beds of New York and the Alleganies, through the 

 Upper Silurian, Devonian, and Carboniferous eras, though so many thou- 

 sands of feet thick, were made within the Interior sea out of material derived, 

 so far as non-calcareous, from the wear of rocks about it, and that the tidal 

 and other currents of the Interior sea distributed the material. 



This Eastern Interior sea, while closed in the direction of Albany, had, 

 during tbe Niagara period of the Upper Silurian, a wide open way westward 

 over Ontario, Michigan, and Northern Ohio ; and here the tides entered as 

 freely as from the southwest. But afterwards, in the Salina and Lower 

 Helderberg periods, it became much less free, though still open, for the 

 Cincinnati barrier made transitions in these Interior regions easy from an 

 open clear sea to great areas of salt-pans over west-central New York, and 

 still wider regions of salt-water and brackish-water flats, such as the deposi- 

 tions of the Salina and the Water-lime beds prove to have existed. The salt 



