AVERAGE REGIONAL SLOPE 39 



"beveled hills" type of characters which are characteristic of the 

 stage of maturity. 



It is suggested that the upland portion of the Interior Plateaus 

 of British Columbia be taken as a type of the "beveled hills" form, 

 and that the term therefore be restricted to old erosion surfaces 

 upon which the average regional slopes are from 3 to 6 per cent. 

 The upland of the Plateaus differs from an ideal type in that gla- 

 ciation has removed the soil covering and substituted an irregular 

 mantle of drift. 



The term "beveling" was introduced into physiographic litera- 

 ture by Tarr. 1 He applied the term to the process of the cutting 

 down of certain of the peaks and ridges on a land form, by differ- 

 ential erosion, to approximately uniform elevations. According 

 to Murray's New Dictionary one of the meanings of "to bevel" is 

 "to reduce (a square edge) to a more obtuse angle." As used in 

 this paper the adjective "beveled" is meant to suggest that the 

 land form so designated has been reduced to one on which nearly 

 uniform sky lines are a common characteristic, and one upon which 

 ridge tops have broadened or become rounded in cross-section; 

 that is, the angles which ridge sides make at their crests have 

 been increased to obtuse angles. "Hills" are meant to suggest that 

 the land form is composed of numerous eminences of moderate relief 

 and of smooth and rounded contours. Except in so far as it sug- 

 gests reduction from a higher and more rugged form, the term 

 "beveled hills" is intended to be descriptive, and is not meant to 

 suggest the agencies by which reduction was effected. 



GENETIC SIGNIFICANCE OF REGIONAL SLOPES 



The desirability of a subdivision of this kind is that it will 

 stimulate the gathering of data on the slopes of old erosion sur- 

 faces, and that it places definite limits on the term "peneplain." 

 The value of such data and of such a restriction have been referred 

 to before. An added argument in its favor is that the subdivision 

 is based upon a factor which is of genetic significance in the develop- 

 ment of land forms. For the slopes of a topographic form are not 

 only one of the results of its development, but the amount of slope 



1 R. S. Tarr, "The Peneplain," Am. GeoL, XXI (January-June, 1898), 351-70. 



