ANCIENT WATER LEVELS OP CHAISIPLAIN-HUDSON VALLEYS 241 



eastward probably into union with one or more of the morainal 

 stages described by Taylor in the Berkshire hills of northwestern 

 Massachusetts. About the end of the glacier, clays were depos- 

 ited at Newburg and Fishkill Landing in the northward extended 

 body of water whose shore lines are marked by the earlier formed 

 deltas and terraces of the ice retreat. 



From this time on till later in the history of the recession, the 

 retrogression of the ice front is marked by partially revealed 

 gravel and till deposits in the Hudson gorge or over the surface 

 of the rock benches which border it. As the ice front passed the 

 mouths of streams which enter the Hudson, their volume and 

 load of sediment was vastly increased by contributions from the 

 ice on their north bank, thus determining the time of their maxi- 

 mum constructive effect. The result of these changes is seen 

 in the horizontal alternation of deposits of till and gravel with 

 finer sediments at intervals of a few miles in the banks of the 

 gorge from the Highlands northward as far as Rhinebeck north 

 of which region the coating of a later group of clays laid down 

 far beyond the ice front of their time partly conceals the full 

 history of the disappearance of the ice from the immediate vicinity 

 of the gorge. 



As soon as the Mohawk valley was opened a large contribution 

 of water charged with fine sediment came into the Hudson valley 

 from that direction and for some time later was distributed far 

 and wide to the south in the form of clays which may be traced 

 as an almost continuous sheet over the rock benches and in the 

 gorge itself as far south at least as Saugerties. The same body 

 of clays extends northward along the Hudson banks at least to 

 the southern border of the Fort Edward district and probably it 

 is the same clay formation though perhaps of a somewhat later 

 stage of deposition which is traceable through the valley of Wood 

 creek into that of Lake Champlain. 



The deposition of this clay appears to have been interrupted 

 by an advance of the ice into the Fort Edward district as far 

 south as the northern mouth of the deeper Hudson gorge. 



The waters of Lake Albany, in which this clay was deposited, 

 appear to have been shallow and to have covered the rock benches 

 of the gorge as far south as Saugerties, possibly also at Rondout 



