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NEW YORK STATE MUSEUM 



which the streams lay down along the ice margin and in contact 

 with it. As the gravels and sands are dragged along and 

 deposited further out, they will begin to cover the earlier de- 

 posited clays, and thus we shall have as the progressive steps in 

 the deposition of a harmonic series of sediments the appearance 

 in the lower and outer portion of the delta of an earlier set of 

 clay beds and a later set of beds of gravel and sand. While the 

 beds seen in any one vertical section are truly older at the bottom 

 and newer at the top, the difference in age in this case is very 

 slight. 



Since the clays south of Cedar pond brook rise higher than 

 those north of the head of the delta at North Haverstraw it 

 is probable that the upper part represents the earlier clay deposits 

 of this stage of delta building instead of some far earlier deposits 

 like those seen near Stony Point. These clays will be found again 

 in Croton point and further discussion of their origin may be 

 deferred till that deposit has been described. 



Croton point. On the east side of the Hudson, Croton point 

 presents one of the most striking features of glacial origin in the 

 course of the river from its source to the sea. There are larger 

 and thicker deposits of drift but none which intrude themselves 

 so forcibly on the plain map of the State. Croton point is again 

 a complex of glacial deposits. The outer insular portion of this 

 cape is partly of ice-laid morainal origin. All about the shores of 

 Tellers point northward to the northern unnamed point the beach 

 is lined with large glacial boulders. Dark boulders of a basic 

 igneous rock are common and boulders of a red conglomerate un- 

 doubtedly from the Triassic strata underlying the Palisade range 

 occur being derived probably from the basal strata of that forma- 

 tion in the bed of the river. On the western side of the north point 

 the deposit of till with boulders and gravels rises high above the 

 water level, showing that the ice front lay against this edge of 

 the deposit, and as pointed out on page 99 that the ice front of the 

 Haverstraw moraine crossed the river at this point, resting on 

 the rocky shore of the eastern bank at Croton Landing where 

 again thick deposits of till occur. The approximate position of 

 the ice front at this stage is shown in the annexed sketch map 



[fig. 93. 



