SO Cairnes — Some Suggested JVeio Physiographic Terms. 



In regions having interior drainage, eqniplanation is also 

 nearly everywhere in evidence. There, wind action, stream 

 and water action, and the various other subaerial destructive 

 and constructive physiographic forces, slowly diminish the 

 relief by constantly removing material from the higher, gener- 

 ally peripheral areas, and depositing it on the basin floors of 

 the various centripetal systems, thus causing all the local base- 

 levels to rise. This is a true equiplanating process, as by it the 

 relief is reduced and the surface of each region so affected 

 tends to become more and more plain-like in contour, and in so 



Fig. 2. 



Fig. 2. A view of the upland surface. 3,500 feet above sea-level, along 

 the 141st meridian (the Yukon-Alaska International boundary) at north lati- 

 tude 66° 51'. Eqniplanation is here active ; the material composing the 

 abrupt-edged limestone residual is being disintegrated and dissolved and 

 subsequently added to the accumulations of debris that fill the adjoining 

 bed-rock depressions. 



doing no loss or gain of material is involved. In many such 

 regions having interior drainage, however, more or less fine 

 material is exported by the wind, as explained under " depla- 

 nation," causing the general level to become reduced. The 

 gradational agents are, nevertheless, truly equiplanating and 

 operate, to a large extent, independently of the deplanating 

 wind action. 



Equiplanation is particularly effective, in regions having 



