BASELEVEL, GRADE AND PENEPLAIN 83 
Kummel writes of the ‘long erosion which resulted in the 
Cretaceous baselevel”’ of Connecticut (379). 
Willis says : 
The tendency is in time to reduce the land toa gently sloping plain, 
which extends from the sea to the headwaters of the rivers. Such a plain is 
called a daselevel. .... A surface, which is almost, but not quite, a baselevel, 
is called a peneplain (1895, 188, 189). 
Hill describes a persistent bench near Panama as: 
Representing an ancient baseleveled plain, which will be described as the 
Panama baselevel (197). 
An essay by Van Hise describing a ‘‘baseleveled plain” is enti- 
tled ‘‘ A Central Wisconsin Baselevel” (57). 
I have had a small share in a similar use of ‘‘ baselevel;” for 
example : 
The general upland surface of the Highlands [of New Jersey] is an old 
baselevel, in which valleys have been cut in consequence of a subsequent 
elevation (1889, 20: see also Davis and Wood, 384). 
A review of the above citations, whose number might be 
greatly extended, shows that ‘‘ baselevel”’ is given very different 
meanings by different writers. These meanings are: an imagi- 
nary level surface in extension of that of the ocean (the convex 
geoid surface); an imaginary mathematical plane; an imaginary 
surface sloping with the mature or old streams of its area; the 
lowest slope to which rivers can reduce a land surface; a level 
not much above that of the sea; aslow reach ina stream; a con- 
dition in which rivers cannot corrade or in which they are bal- 
anced between erosion and deposition; a certain stage in the 
history of rivers when vertical cutting ceases and their slope 
approximates a parabolic curve; an ultimate planation; and a 
plain of degradation. 
Limitation of the meaning of ‘‘baselevel.’’—The diversity of the 
above definitions may be better perceived when it is noted that 
they are expressed in terms of very unlike quantities: imaginary 
surfaces, level, plane, or warped; alow slope; apart of ariver; a 
condition of river development; a stage in river history; an ulti- 
mate planation; and an actual geographical form. It is evi- 
