SOME STAGES OF APPALACHIAN EROSION. 519 



The following paper was then read : 



SOME STAGES OF APPALACHIAN EROSION 

 BY ARTHUR KEITH 



Contents 



Page 



Introductory 519 



General features of the southern Appalachians 519 



Drainage basins 519 



• Surface forms 520 



Variations of level 521 



Features of the Tennessee basin , 522 



Peneplain groups i 522 



Clinch section 523 



Unaka-Blue Ridge section 523 



Summary 524 



Introductory 



In the southern Appalachians the phenomena of subaerial erosion are shown 

 under every phase except those of arid and glacial conditions and in nearly eveiy 

 stage of development from alpine forms to complete reduction. The work of 

 degradation, which is controlled by the characteristic features of Appalachian 

 structure and stratigraphy, itself emphasizes these features most strongly. Various 

 publications have been made of facts and theories connected with the erosion and 

 uplift of the Appalachians. Willis * has described a characteristic Appalachian 

 baselevel plain ; Davis f has published theories and descriptions of peneplains in 

 New Jersey and Pennsylvania ; Hayes and Campbell J have published a descrip- 

 tion, with a theory of the deformation of two peneplains shown at intervals over 

 the southern Appalachians ; the present author^ has described the nature and de- 

 formation of five Appalachian peneplains in northern Virginia and Maryland, and 

 various other publications have touched upon minor features of erosion. The sub- 

 ject is still far from fully grasped, however, and even the broad processes of the 

 production of the present surface are a subject for discussion. The purposes of this 

 paper are to classify the peneplains of the southern Appalachians according to the 

 ideas expressed previously by the author, and to oppose the extreme application of 

 the theory of deformation as advanced by Messrs Hayes and Campbell. For these 

 objects a systematic presentation of details need not be given. 



General Features of the southern Appalachians 



DRAINAGE BASINS 



Four great groups of streams drain the southern Appalachians and are carrying 

 on the work of erosion. First of these are the tributaries of the Tennessee river 



* National Geographic Magazine, vol. i, no. 4, pp. 291-300. 



Ibid., vol. i, 1889, pp. 183-253. 

 fProc. Bost. Soc. Nat. Hist., vol. xxiv, 1889, pp. 3G5-423. 



National Geographic Magazine, vol. ii, 1890, pp. 81-110. 



Bull. Geol. Soc. Am., vol. 2, 1890, pp. 545-581. 

 I National Geovcraphic Magazine, vol. vi, 1894, pp. 63-126. 

 § Fourteenth Annual Report of the Director of the U. S. Geol. Survey, 1892-93, pp. 366-394. 



