THE CRETACEOUS PERIOD 251 



" Cretaceous Peneplain/' because of its best development during 

 the Cretaceous period (Fig. 155). This vast plain extended over 

 the areas of the Appalachian Mountains, Piedmont Plateau, all 

 of New York state, the Berkshire Hills, and the Green and White 

 Mountains. Its most perfect development was in the northern 

 Appalachians as, for example, from east-central Pennsylvania to 

 Virginia, where hard and soft rocks alike had been so thoroughly 



A 



y?M 



fy$5Sas**^d> ■ e r , « 







Fig. 155 



Diagrammatic section through the Atlantic slope at about the latitude of 

 northern New Jersey, showing the structures and relations of the various 

 physiographic provinces as they now exist. 



A to B, folded Paleozoic strata of the Appalachian Mountains, with hard 

 strata standing out to form the ridges; B to C, Piedmont Plateau, con- 

 sisting of highly folded, and metamorphosed rocks of pre-Cambrian and 

 early Paleozoic ages; C to E, Triassic strata, showing tilting and faulting of 

 the beds and mode of occurrence of a sheet of igneous rock (D) which 

 outcrops to form low ridges; E to H, Coastal Plain, consisting of com- 

 paratively thin sheets of unconsolidated sediments; E to F, Cretaceous 

 beds; F to G, Tertiary beds; G to H, Quaternary beds; H, present coast 

 line. 



The dotted line represents the peneplain character of the surface, except for 

 the tilting, toward the close of the Mesozoic era. (After W. J. Miller, N. Y. 

 State Mus. Bui. 168.) 



cut down that no masses projected notably above the level of the 

 low-lying plain. 



Farther northward, however, over New York and western 

 New England, its development was less perfect, so that certain 

 masses of harder rock stood out more or less prominently above 

 the general level of the plain. 



As Berkey says: "The continent stood much lower than now. 

 Portions that are now mountain tops anu-iuAe crests of ridges 

 were then constituent parts of the rock floor of the pene- 

 plain not much above sea level. . . . The ridges and valleys, the 

 hills, mountains, and gorges of the present were not in existence, 



