040 NKW YORK STATE MUSEUM 



point imineil is composed of stratiried gravtils and sands with yel- 

 lowish layers, dipping nearly flat on the north side of Hie suniniit 

 hut inclining to 3n^ south, and evidently truncated on the west. 

 This sectii»n was exposed in June 1900 in the excavation for a 

 hirge house then in pnx'ess of erection. Other small sections in 

 ilriveways along the western slope exhihited straiilied beds dip- 

 ping in j)laces 5° northward and usually eroded. On the western 

 slope bouldery till, reddish from oxidation, appears about 5 feet 

 thick; hut till is wantiui; over the summit, which evidently has not 

 ?K'en run over by the ice. 



A complete section through this hill would be required U) satisfy 

 the needs of an exact analysis of its mode of formation ; Ijut the 

 gravel beds dipping 30° south at the sumniit on the southern face 

 of the knob appear clearly to j)lace it in the group of glacial cones, 

 f«>rmed along the ice front, homologous to the alluvial cones which 

 form in the lower course of a drainage furrow on the side of a 

 mountain valley, with this difference, that the mass at whose base 

 it was formed, being ice, has melted away. 



The glacial gravel in these cones and mounds arranofed aloncr the 

 ice front, would appear to have been washed off from the top of 

 the thinning ice border or to have issued from tunnels in the upper 

 part of the ice. The character of the material in Harbor hill gives 

 a decisive clue to its origin. The gravels are mostly yellow (piartz 

 from tiie older Pleistocene deposits which flank the moraine on the 

 north. They probably have not been transi)orted for distances 

 greater than 1(» miles; they may have been caught up from the 

 base of the ice within ?, or 4 miles. At all events, they are locally 

 derived material already existing in the district when this advance 

 of the ice was accomplished. 



The elevation of Harbor hill, nearly 40() feet above present sea- 

 level, alTords conclusive evidence as to the least estimate which may 

 be made on the bight of the ice front at this point. This bight was 

 at least 4no feet and probably more. This least elevation agrees 

 well with the data found by Smock^ in the longitudinal valleys of 

 northern New Jersey, where ice tongues rose northward tor a few 



MniK k. J. C. On tlie siirfafe limit or thickness of the continental ghicier in 

 N«w .lersc-y unci adjacent sUtes. Am.' jour. sci. 8(1 ser. 1882. 25 : 339-50. 



