15 ANNALS NEW YORK ACADEMY OF SCIENCES 



CONSTRUCTIONAL FORMS 



Plains and Plateaus. — Study of the constructional group of land forms 

 is introduced by consideration of plains and plateaus characterized by a 

 simple and almost horizontal structure. The subject begins most natu- 

 rally with coastal plains. The well denned elements of the recent coastal 

 plain of the Atlantic coast, comprising its oldland in southern New Eng- 

 land, New York, northern New Jersey, and the Piedmont further south; 

 its inner lowland partly drowned in Long Island Sound, Lower New 

 York and Sandy Hook Bays, then followed by the main transportation 

 routes between New York and Philadelphia, occupied by the Delaware 

 River from Trenton to the Bay, and thence southward; the features of 

 the fall line seen in the rapids at Trenton, N. J., the falls of the Schuyl- 

 kill at Philadelphia, the Great Falls of the Potomac at Washington, and 

 those of the James River at Richmond; the main cuesta forming the 



Fro. 12. — Profile view of the coastal plain cuesta, near Clementon, New Jersey 



It is 15 miles east of Philadelphia and a few miles south of Camp Dix, which is 

 built upon the flat back slope of the cuesta. The soil here is loose and unconsolidated, 

 is very sandy and dry, and supports an open forest of pines and rhododendrons. 



foundation of Long Island, the Atlantic Highlands at Sandy Hook, its 

 ragged front making up the hilly belt of southern New Jersey, its flat 

 surface the pine barrens which incidentally provide a suitable location 

 for Camp Dix, whose site is near the cuesta front, are all features which 

 may be pointed out in much greater detail than here indicated (Fig. 12). 

 The various genetic types of streams — consequent, subsequent, obsequent, 

 resequent, and insequent — can be illustrated by examples almost too 

 numerous to mention. 



In central New York the ancient coastal plain provides even bolder 

 features and somewhat greater variety. Its oldland in Canada and the 

 Adirondacks, its inner lowland in Mohawk Valley and the basin of Lake 

 Ontario, its cuestas in the Helderberg Mountains and the Allegheny and 

 Niagara escarpments and many other details could be cited (Fig. 13). 



Stages in the development of a plain or plateau are illustrated by the 

 very youthful drainage systems of the coastal regions of Maryland and 

 Virginia, by the deeper but still youthful dissection of the Allegheny 

 Plateau, by the headwaters of the Susquehanna River in New York, and 



