The wide acceptance and use of inferences concerning the presence and approximate age of the peneplains, covering in the aggregate almost all of the Appalachian Highlands, make the dating of these peneplains a matter of great interest and importance in deciphering the history of the region and in interpreting the sedimentary deposits derived therefrom. Great precision may perhaps never be possible; but on account of the importance of the problem, it seems desirable to examine the data which have been set forth and to add to them if possible. In this paper it is proposed to accept Appalachian peneplains as they are described and to consider them in the light of certain general principles and of published and unpublished data concerning buried peneplains in the Atlantic and Gulf coastal plains. No inferences except those relating to age are discussed, and the proposed modifications are to be regarded only as suggestions. . . .