STUDIES FOR STUDENTS 
BASELEVEL, GRADE AND PENEPLAIN. 
CONTENTS. 
Thesis of this essay. 
The original meaning of “ baselevel.”’ 
Definitions of ‘‘baselevel”’ by various writers. 
Limitation of the meaning of ‘‘ baselevel.”’ 
The balanced condition of rivers. 
Origin and use of the term “ grade.” 
The baselevel surface is complete from the beginning and permanent to 
the end; the condition of grade is slowly introduced and gradually extended. 
The baselevel remains fixed all through an uninterrupted cycle; the 
slope of a graded river must vary as the cycle advances. 
Baselevels are of only two kinds, general (permanent) and local (tem- 
porary); grade includes not only the balanced condition of large and small, 
mature and old water-streams, but that of all kinds of waste-streams as well. 
Plains and peneplains. 
The geographical cycle. 
Denudation and degradation. 
Conclusion. 
List of authors cited. 
Thesis of this essay.—The attention given during the last fifty 
years to the processes and results of land sculpture has naturally 
resulted in the introduction of various new terms, three of which 
stand at the head of this article. It is desired to point out that 
too many meanings have been attached to the first term, ‘‘ base- 
level,’’ and that some of them should be transferred to the other 
two, ‘‘ grade” and “ peneplain.” 
The original meaning of ‘‘baselevel.’—Although the control 
exerted by sea level on river action has long been recognized, 
the importance of the control was more generally perceived by 
American students of geology when it was explicitly formulated 
in the term ‘“baselevel”’ by Powell in 1875. The term soon 
became so popular, especially with American writers, that a 
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