ANCIENT WATER LEVELS OF CHAMPLAIN-HUDSON VALLEYS 93 



The frontal margin runs out into a long spur on the western 

 side ending at about 20 feet above the present sea level. In front 

 of the plain is a flat of fine sands. A well sunk in April 1901 

 southwest of the railroad station reached rock at 67 feet. Above 

 the rock was '^ hardpan/' and above that about 10 feet of clay. 



Van Cortlanclt park plain. The parade ground at Van Cort- 

 landt park on Tibbits brook in the northern part of New York 

 city is a somewhat modified natural plain or terrace whose sur- 

 face is about 20 feet above sea level. It is composed of glacial sand 

 and gravel and is of either late glacial or early postglacial date. 

 The surface of the plain now shows no trace of kettle holes, and 

 the slope to the stream on the east and south has no decisive 

 character except it be nearly in front of the ancient manor-house 

 where the slope is marked by a few headstones and also along 

 the southern end of the plain. A few coarse angular pieces of 

 drift rock lie on the slope near the old gravestones. This fact 

 and the manner of ending of the plain in this direction on the 

 broad open valley of a sluggish tidal creek suggest that the plain 

 may have been built in waters confined by a melting remnant of 

 the glacier. It should be borne in mind, however, that direct 

 evidence of the deposition of such gravels and sands in some 

 part of their margin against masses of ice does not in such a 

 situation as that of the Cortlandt park plain exclude the possi- 

 bility of the water level, if such there was to control its upward 

 growth, having been at sea level. 



Certainl}^ the sudden ending of the deposit on the south in a 

 terrace without delta lobes and without evidence of having been 

 brought to this form by the excavation of the drift in the vallej^ 

 below this point makes it probable that the valley toward the 

 Hudson was ice filled, and thus entirely possible that the deposit 

 was made above sea level. In short, the plain at Van Cortlandt 

 park does not demand a higher stand of the sea than that now 

 existing. 



Tappan moraine [,sec pi. 2]. The first definite morainal ac- 

 cumulation in the Hudson valley north of the Narrows is en- 

 countered on the west side of the Palisades immediately north 

 of the New Jersey boundary in the village of Tappan. At this 

 point the Palisade trap ridge is deeply dissected on a northeast- 



