REPORT OF THE DIRECTOR 1920-21 



l8l 



Pleistocene Fauna of the Hudson Valley and its Significance 



No fossils have been reported from the Pleistocene deposits of 

 the Hudson valley south of Croton Point, either from the New York 

 or New Jersey shores. The clays of the Hackensack region, New 

 Jersey, might be attributed either to marine or lacustrine origin 

 (Salisbury, p. 195, 200). The absence of fossils seems to be against 

 the hypothesis of a bay of salt water. However, it is thought 

 probable (ibid., p. 198) that such connections as the bay had with 

 the ocean were perhaps outlets rather than inlets and the discharge 

 of fresh water into the bay after the ice had left New Jersey must 

 have been great. Under these conditions the waters of the bay 

 may not have been salt, or at least not normally salt, which would 

 account for the absence of marine life. 



The most northern point at which Pleistocene 

 fossils have been reported from the Hudson val- 

 ley is at Storm King, 50 miles above New York 

 (Shimer, p. 488, 489). The specimens were 

 found in drilling a series of holes across the 

 Hudson bed and belong to only two species, 

 Mulinia lateralis (Say), of which hun- 

 dreds of specimens were collected, and Trivia 

 trivittata Say, of which there were but 

 few specimens collected. The fossils were found 

 620 feet out in the river from the Storm King 

 shore, 40 feet below the bed of the river, which 

 is about 120 feet below the present river or sea 

 level at that point. Shimer describes this ^s 

 a dwarf fauna which in the abundance of 

 Mulinia lateralis suggests Pleistoceen 

 age. He points out that the Hudson today 

 is brackish at Storm King and as far north as 

 Poughkeepsie and that heavier sea water might 

 still come up in sufficient amount to furnish a 

 marine habitat even under quite fresh sur- 

 face conditions ; but that it was not ascertained 

 whether there are any marine forms in the 

 present bed of the stream. Fairchild (1919, 

 p. 16) states that salt-water organisms pass up 

 the Hudson only to the Highlands. 



The two species found at Storm King live at Fi s- 2 Sketch map of 



present off the New England and New Jersey Hudson river valley 



1 . , , ,- -, ,i r 1 1 showing localities 01 



coasts, mnormalmanneorbutslightlyfreshened wherem arine Pleistocene 



water; and in these localities are considerably fossils were found. 



