352 The A})icrican Geologist. June, i8£8 
or a fossil vertebrate; and not only are single peneplains found 
in a given district, but oftentimes several of different ages. 
It is perfectly certain that many of the so-called peneplains 
have been announced without any semblance of proof. But 
it is not against these that I write, for the author of the pene- 
plain idea has himself urged more careful study before the 
announcement of a peneplain, — advice which has not been 
generally followed. The literature of geology is becoming 
overburdened with peneplains, and the geological history and 
geography of the past are often interpreted upon the basis of 
these. If any of the peneplains are well founded, their dis- 
covery and correct interpretation form an important factor 
in geological investigation. On the other hand, if they are 
wrongly interpreted, and the entire idea is incorrect, geological 
literature is becoming seriously confused, as it has been at 
times in the past, when erroneous ideas have prevailed in 
large measure as the result of authority. Should this be the 
case with the peneplain, the time has long since passed when 
the error should have been detected. Believing as firmly as 
I do that the peneplain explanation is incorrect, I feel that I 
should do wrong to longer delay the publication of my rea- 
sons. 
At the same time, while I have a firm belief, as stated, 
doubts concerning the validity of this position cannot help 
arising, for the views that I hold seem opposed to those of 
the larger number of leading American geologists. I may 
be wrong, and the weight of authority would seem to indicate 
that I am. I hope that my paper will call out a discussion 
and that if I am wrong, the case will be proved beyond ques- 
tion. Even if this is the outcome of this paper, the discussion 
may perhaps have a salutary effect in putting a stop to the 
reckless announcement of unproved peneplains, and should 
lead all geologists to give a more careful study before they put 
forward the announcement. 
Definitio/i of a Peiieplain. — A peneplain is "a nearly 
featureless plain" produced by subaerial denudation.* These 
are not true plains, but "nearly always possess perceptible 
inequalities, amounting frequently to two or three hundred 
*Davis: Am. Journ. Sci., 1889, ser. III., vol. XXXVII., p. 430. 
