O/O E.W.SHAW AGES OF APPALACHIAN PENEPLAINS 



13. Uplift southwestward and erosion to baselevel. 



14. Uplift warping and degradation to Tertiary baselevel; deposition of 

 Pamunkey and Chesapeake. 



15. Depression and deposition of Lafayette. 



16. Uplift and erosion to Lower Tertiary baselevel. 



17. Uplift warping and erosion to Pleistocene baselevel ; deposition of high 

 level Columbia. 



18. Uplift and erosion to Lower Pleistocene baselevel ; deposition of low level 

 Columbia. 



19. Uplift and present erosion. 



Hayes/ concerning the age of the Cumberland peneplain, says : 



"As to the length of time which it [its development] covered there can be 

 little question, as its limits are tolerably well fixed, the beginning being the 

 emergence at the close of the Carboniferous and the end being the uplift near 

 the close of the Cretaceous." 



Keith/° however, says that "Appalachian degradation was marked l)y 

 at least seven periods of approximate rednction. Each of these produced 

 a vast series of peneplains which appear in various forms at the present 

 day." Later work has convinced him^^ that peneplains of several other 

 ages are present in the province. 



It is worthy of note that all physiographers who have written on the 

 subject seem to infer that parts of all peneplains formed since Carbon- 

 iferous time remain to the present day, the oldest and highest remnants 

 being parts of the first peneplain formed. Mr. Keith,^- however, now 

 states that he did not intend to express such an opinion in the foregoing 

 quotation, and does not believe that parts of all peneplains have been pre- 

 served, since some of small extent may have been completely removed by 

 later and larger ones. 



From a study of the region l3etween northern Massachusetts and the 

 Potomac, BarrelP" reaches the conclusion that instead of remnants of 

 one or more peneplains the region shows eleven sea-cut terraces, two of 

 which are as old as Cretaceous. 



Chamberlain and Salisburv^* sav that "the Kittatinnv baselevel was 



" C. W. Haj'es : Physiography of the Chattanooga district in Tennessee and Alabama. 

 U. S. Geol. Survey, Nineteenth Ann. Kept, pt. 2, 1890, p. .SS. 



1" A. Keith: Some stages of Appalachian erosion. Bull. Geol. Soc. Am., vol. 7, 1895, 

 p. 524. 



^'^ Oral communication. 



^- A. Keith : Oral communication. 



^".Joseph Bavrell : IMedmont terraces of the northern Appalachians and their mode of 

 origin (abstract) ; post-.Turassic history of the northern Appalachian (abstract, with 

 discussions). Bull. Geol. Soc. Am., vol. 24, Dec. 28, 1913, pp. 688-696. 



'^ T. C. Ghamlierlain and T{. D. Salisbury: Geology, vol. 1, 1904, p. 159. 



