GLACIAL AND POST-GLACIAL HISTORY 647 



appearance the more applicable the explanation becomes. If the 

 Hudson water body existed until the ice had retired to the Bouquet 

 River, or beyond the Saranac, as is considered in the various hypothe- 

 ses stated for the time of origin of the Higher Glacial Lake Champlain, 

 then there was a long time for the production of shore terraces. The 

 time necessary to make the secondary deltas noted on the Batten 

 Kill and the Hudson River would seem to be ample for the develop- 

 ment of distinct wave-wrought terraces, and it is in this part of the 

 valley only that features have been observed that may be assigned 

 to wave-action, but it is surprising that they are not better developed 

 here, (d) There is evidence that the water-level was not constant. 

 Possibly there were two things to make it inconstant: first, the 

 cutting of the outlet, and, second, crustal movement. The first 

 could be true, of course, only if the Hudson water body was a lake. 

 The second could be true under either hypothesis for the origin of the 

 water body, and, as mentioned above, is necessary for the disappear- 

 ance of the water body under either hypothesis. 



Altogether the shght development of wave-wrought features in 

 the Hudson is unexpected, and the above explanations do not seem to 

 be wholly satisfactory, especially when it is recalled that under 

 apparently very similar conditions distinct wave- wrought features 

 were made in the Champlain region. The writer is forced to believe 

 that a more detailed examination of the Hudson region will bring to 

 light more evidence of wave-action. 



Features unexplained by the salt-water hypothesis. — Certain features 

 are present which are in accord with the lake hypothesis, but not 

 with the salt-water hypothesis. There are certain features not 

 present which seem to be required by the latter hypothesis, but not 

 by the former. If the Hudson water body was an arm of the sea, 

 the presence of some of these features and the absence of others 

 must be accounted for. These features are: (i) absence of dis- 

 tinct wave- wrought features at the outer edge of the Brooklyn-Perth 

 Amboy moraine at the levels required by the hypothesis; (2) presence 

 of the overwash plain on Staten Island and Long Island without 

 distinct features to be ascribed to wave-action; (3) entire absence of 

 life certainly marine in the deposits made in the Hudson water body; 

 (4) 'apparent absence of tidal distribution of muds in the Hudson 



