20 



ANNALS NEW YORK ACADEMY OF SCIENCES 



Mountains, and in fact all of New England, which is only the stump of 

 a worn-down complex mountain mass extending southward in the New 

 Jersey Highlands (Figs. 1, 2, 3). New York City (Fig. 14) is a part of 

 this area. In Pennsylvania, Maryland, and Virginia we find this same 

 type of crystalline rock appearing again in the Piedmont (Fig. 26) and 

 the Blue Kidge portion of the older Appalachians. 





^*:::x'\? : At^ : &y. .0'^ 



'\t.\ ')r<W 



" — ,_,:! 111- jJtf i~*J&R~XZi 



Musconefcong fo//ey near /Jadreltstow/n 



Fig. 16. — The Cretaceous and Tertiary levels as seen looking tcest from the oase of 

 Schoolcy Mountain, south of Hackettstoicn, New Jersey 



SCrst- Pent, 



77?g Delaware U/afer Gap reg/on . 



Fig. 17. — Diagrammatic representation of the main relief features in the Delaware 



Water Gap region 



The Cretaceous peneplane is preserved on the hard resistant Shawangunk conglom- 

 erate, which forms Kittatinny Mountain, and on the pre-Cambric crystallines which 

 form the New Jersey Highlands to the east. The Tertiary peneplane on the floors of 

 the valleys and the post-Tertiary stream dissection are distinctly indicated. 



Volcanic Mountains. — Topographic features resulting from volcanic 

 activity in our neighborhood are limited mainly to the trap ridges of 

 Connecticut (Fig. 18), and the Triassic belt of New Jersey (Fig. 29), 

 Pennsylvania, and Virginia, where the Palisades, the Watchung Moun- 

 tains, and Cemetery Eidge at Gettysburg provide examples worthy of . 

 mention. In New England the roots of old volcanoes like Ascutney 



