650 CHARLES EMERSON PEET 



suggestions have been made: (i) The waters were cold while the ice 

 was near. (2) The waters were muddy while the ice was near. (3) 

 The waters were freshened because of the great territory — at one 

 time the Great Lakes drainage basin — drained into this water body, 

 and because of the shallow sill over which httle salt water could 

 pass. 



(i) In regard to the first suggestion it may be said that the waters 

 were cold, but they were decreasingly cold as the ice retreated 24a- 

 300 miles and more northward. In Greenland, at the present time, 

 marine life is abundant in the waters close to the ice-edge,' so that 

 even if the waters were cold it does not appear to be a sufficient reason 

 for the absence of salt-water life. Further than this, marine life 

 invaded the Champlain region soon after the ice had retreated across 

 the St. Lawrence and permitted the sea to enter. The fact that it 

 failed to do so during the much longer time it had to get into the 

 Hudson from the south while the ice was retreating northward 

 argues strongly against the salt-water hypothesis. 



(2) The waters were muddy. This argument would hold good 

 so long as the ice was near. When at a greater distance, the argu- 

 ment does not hold good, for it seems to be true that there was com- 

 paratively Httle deposition of muds at a distance from the ice. Were 

 it not so, the kames and other ice-molded forms at low levels would 

 have been buried. The presence of marine life in the clays on the 

 coast of Maine, and also in somewhat younger clays in the Lake 

 Champlain region, indicates that marine life could exist while the 

 deposition of considerable fine sediment was taking place. The 

 explanation of the absence of life because of the muddiness of the 

 waters therefore does not carry conviction with it, especially since 

 there was so much opportunity for the introduction of life after the 

 ice had retreated a great distance and the waters had become clear. 



(3) The water was kept fresh because of the shallow sills over 

 which the salt water had httle access. This is perhaps the best 

 explanation offered.^ It necessitates a higher altitude at the east 

 end of Long Island Sound than the present; otherwise there would 



1 Verbal communication of Professor Chamberlin. See also R. D. Salisbury, 

 Glacial Geology of New Jersey, p. 513. 



2 See R. D. Salisbury, Glacial Geology of New Jersey, Final Report of the State 

 Geologist, Vol. V, pp. 511-13. 



