Dissection of Schooley peneplain and development of Harrisburg peneplain on belts of nonresistant rock 



Uplift and dissection of Harrisburg peneplain and development of Somerville peneplain on the weakest rock belts 



Allegheny Front* — * 

 APPALACHIAN PLATEAU — ♦ 



Ridge and Valley belt 



NEWER APPALACHIANS 



-Great Valley-#-Readingprong-»TriasLovvl'd-»- Piedmont ,0- 



-*— OLDER APPALACHIANS ^-*COASTAL PLAIN 



Uplift and dissection of Somerville peneplain to give present conditions 



Fig. 10.10. Late Tertiary and Quaternary stages of epeirogeny and erosion in the Appalachians. 

 Reproduced from Johnson, 1931. Diagrams 7, 8, and 9 from top to bottom. 



145 



