Abstract
The writer reviews certain problems regarding peneplains, and concludes as follows.
1. The so-called peneplains are divided into two kinds according to the manner and position of their origin: one is a peneplain which is concerne with the base-level of the sea and is formed on land of subaerial origin, the other a peneplane formed under sea level by marine agencies.
2. A peneplain is one stage between an old stage (a subdued mountain stage) and a peneplane.
3. Two types of peneplains have hitherto been considered, one de MARTONNE's type, which is mainly the result of subaerial denudation and the other CHAMBERLIN's type, mainly the result of the lateral erosion of rivers.
4. Martonne's type may be regarded as the normal one, and Chamberlin's type as the abnormal, so far as Japanese climates concerned.
5. A thorough study of peneplanation requires a study of weathering soil layers.
6. The nature of a weathering soil layer may be taken as one of the indicators in ascertaining the difference between a subdued mountain and a peneplain.
7. The views hitherto held with respect to the land form of a peneplain have been various. Most of them, however, have been very ideal and imaginal, lacking in positive evidences, so that the writer of this article summarizes the methods of positive evidences which have already been adopted.
8. More consideration and testing than have been formerly done are required to show how groups of almost the same height of summits and spurs have been formed.
9. One of the so-called up-lifted peneplains, which is assumed from the projected profile method, may have to do with its rock structure.
