GLACIAL AND POST-GLACIAL HISTORY 649 



least as high as the present when these overwash plains were made, 

 and higher than that when the gaps in the moraine were being cut, 

 with enough subsequent depression to give the sea access, thus 

 forming the Hudson water body. Such a crustal movement is the 

 opposite of what would be expected as the ice retreats. 



3. Absence of life certainly marine. — The only fossils that have 

 been found in deposits in the Hudson water body are: (i) sponge 

 spicules, fresh- water diatoms,' and worm tracks at Croton; and (2) 

 leaves of Vaccinia oxy coccus at Albany.' No marine fossils have 

 been found, unless the sponge spicules are such, and their identifica- 

 cation, it seems, is uncertain. The presence of fresh-water diatoms 

 is not necessarily fatal to the hypothesis of a salt Hudson water body, 

 for they may have been brought into the salt water by the streams 

 and deposited with the sediments in the salt water. If the sponge 

 spicules are those of salt-water sponges, and if they were found in 

 clays which antedate the recent depression, they settle the question 

 of the origin of the Hudson water body.^ x^lthough there is an 

 entire absence of life certainly marine in the deposits of this time 

 throughout the entire stretch of 240-265 and possibly more than 

 300 miles through which the Hudson-Champlain water body extended 

 (see Fig. 22), in the northern portion of the same region there is 

 abundant evidence at low levels of marine life, which came up the St. 

 Lawrence after the Hudson-Champlain water body had disappeared. 

 Unless there is a sufficient explanation, this must be admitted as a 

 strong argument against the salt-water hypothesis. However, it 

 must be admitted that there is likewise a paucity of any forms of life 

 in the Pleistocene deposits of the Hudson Valley. In explanation of 

 the absence of marine life in this hypothetical long arm of the sea three 



' See footnotes 3 and 4, p. 454. 



2 These sponge spicules were reported from Croton by Mr. Heinrich Ries in 1895. 

 Since the above was written and first placed in the hands of the printer, word has been 

 received from Mr. Ries that the sponge spicules are those of species not confined to 

 salt water. The exact locality at Croton from which the specimens came is also a 

 matter of some uncertainty. That they came from 20 feet below sea-level and were 

 found in solid lumps of clay is certain, however. Inasmuch as some of the clay used 

 at Croton for brick-making has accumulated in the Hudson estuary since the recent 

 depression, it is possible that the clay in which these specimens were found was deposited 

 long after the disappearance of the Hudson water body, and that therefore the fossils 

 mentioned have no bearing on the origin of the Hudson water body. 



