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NEW YORK STATE MUSEUM 



found in earlier proglacial clays. The water body in which the 

 Albany clays were formed appears to have spread over the rock 

 terraces and across the middle Hudson valley at a time when 

 the region on the south rose above the water level, confining 

 the waters to the excurrent stream lying within the gorge. The 

 land must have been tilted to the north in comparison with its 

 present attitude to have brought about such a distribution of 

 effects. The well known phenomena of the submarine Hud- 

 son require also to be explained. While it is difficult to deter- 

 mine at what precise epoch the erosion phenomena there pre- 

 sented had their origin, the theory of high elevation on the south 

 at this time is rendered permissive by the knowledge we have 

 of the old channel. 



DISTRIBUTION OF KETTLE HOLES MARGINAL TO THE HUDSON AND CHAM- 

 PLAIN VALLEYS 



The accompanying plate [pl.28] represents the position and 

 altitude of the kettle holes in the gravels and sands marginal to 

 the Hudson river and the New York side of Lake Ohamplain. 

 Some of these kettles, as on the Brooklyn sheet are in moraines, 

 but most of them are in plains of gravel and sand marginal to 

 masses of ice which lay at one stage or another in the valley. 

 Excepting the type of kettle which occurs in the Brooklyn 

 moraine, those northward along the Hudson and Ohamplain in- 

 variably represent the melting out of detached or buried blocks 

 of ice from local deposits of gravel and sand which were at their 

 time undoubtedly above sea level and presumably, on account of 

 the barrier which the ice of their margin imposed, in an embar- 

 rassed drainage and hence above the level of standing waters 

 farther along in the drainage system toward the sea on the south. 



Such of these shallow depressions as came within the reach of 

 the clay-bearing waters or later deposits of gravel and sand would 

 have been buried. Thus it is strongly probable that the lower limit 

 of kame kettles in the Hudson and Ohamplain valley lies at or 

 above the upper limit of local submergence whether by long con- 

 tinued glacial lakes or the incursion of the sea. The lines repre- 

 senting on one hand the lower limit of kettles and on the other 

 the upper limit of standing bodies of water should roughly corre- 



