LOBECK, NEW YORK CITY, A PHYSIOGRAPHIC CENTER 



9 



developed on the broad valley floors represents the second cycle, and 

 finally the post-Tertiary trenching is the work of the present erosion 

 cycle. No better location can be cited for the observation of these ele- 

 ments of the topography than near Hackettstown, New Jersey (Fig. 15), 

 although they exist almost anywhere in the newer Appalachian belt. 

 Even in the gorge of the Hudson Eiver through the Highlands, the 

 Tertiary cycle is preserved by a great bench or terrace especially well 

 developed on the west side of the stream, a feature readily seen by the 

 traveler from the cars of the New York Central, or even better from 

 the boats on the river (Fig. 5). West Point is apparently built upon 

 part of this bench. 



With rejuvenation resulting from uplift there should be considered the 

 alternative possibility, that of depression, which may or may not impose 



(field sketches 



The Hudson River High/and^ 



Fig. 5. — Sketches in the Hudson Highland* 



Showing the characteristic expression of the topography as influenced by the Cre- 

 taceous peneplane on the tops of the mountains and the Tertiary peneplane preserved in 

 an intermediate bench standing two to three hundred feet above the river. 



old age characteristics upon the streams involved. There are no more 

 suitable examples of a drowned coast with embayed river systems to be 

 had than the northeastern shores of the United States. The ragged and 

 bold coast of Maine and eastern New England, Narragansett Bay with 

 its dismembered headwaters, the great fiord of the Hudson Eiver from 

 New York to Albany, the drowned inner lowland of Long Island Sound 

 and New York Bay, Delaware Bay, and, finest and largest of all, the 

 depressed portion of the Susquehanna Eiver system now comprised in 

 Chesapeake Bay and its numerous arms; these and many other smaller 

 examples may all be cited at this time. 



Then, aside from elevation or depression, there may be certain acci- 

 dents in the life of a stream which cause it to change its behavior in the 



