AVERAGE REGIONAL SLOPE, A CRITERION FOR THE 

 SUBDIVISION OF OLD EROSION SURFACES 1 



LEOPOLD REINECKE 



Geological Survey of Canada 



CONTENTS 



Introduction 



Method of Measuring Regional Slopes 



Value of the Measurement of Regional Slopes 



a) In Determining the Agencies Which Have Formed the Surface 



b) In Separating Forms Due to Different Erosion Cycles 



c) In Furnishing Accurate Data for the Quantitative Measurement of 

 Earth Movements 



Value of Certain Criteria for Peneplanation 

 Proposed Subdivision 

 Genetic Significance of Regional Slopes 

 Objections to the Subdivision 



a) The Subdivision Is Arbitrary 



b) An Accurate Average of the Regional Slopes Is Not Easily Obtained 



c) It Entails Added Field and Office Work 

 Summary 



INTRODUCTION 



During the four field seasons from 1908 to 191 1 the writer was 

 engaged in topographic and geologic work in the southern part of 

 the Interior Plateaus of British Columbia. Certain questions 

 which arose in the study of the physiography of that region are 

 discussed in this paper. 



Information regarding the physiography was acquired from a 

 study of the Tulameen and Beaverdell map areas at the Southern 

 end of the Plateaus, of the Kamloops and Shuswap 2 map sheets 

 covering 9,000 square miles to the north of them, and from the 



1 Published by the permission of the Director of the Geological Survey of Canada. 



2 The geological work upon the Tulameen map area was done by C. Camsell, 

 and upon the Kamloops and Shuswap areas by G. M. Dawson of the Geological Sur- 

 vey of Canada. Explorations in the country between these areas have been made 

 by the same men. 



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