THE 
AMERICAN GEOLOGIST, 
Vol. XXIII. APRIL, 1899. No. 4 
THE PENEPLAIN. 
By W. M. DAVIS, Cambridge, Mass. 
[Plate VII.J 
Had it not been for the distractions of foreign travel during 
a year of absence from college duties. I should have sooner 
written a reply to Professor Tarr's article on "The Peneplain" 
that appeared in the Geologist for June, 1898. The delay 
has not, however, been a disadvantage on my part, for it has 
enabled me to talk over the problem with a number of English 
and French geologists and geographers who are interested 
in such matters, and thus to free my reply somewhat from 
individual prejudices. The discussion that Professor Tarr's 
article should awaken will be a welcome one, for as he has well 
said, the peneplain is toO' important a matter to gain an ac- 
cepted position without close scrutiny. The courteous and 
earnest tone of Professor Tarr's essay will, I hope, determine 
the style of those that follov^' it. 
At the outset, allow me to correct the implication that the 
"peneplain idea" was original with me. The name is of mv 
invention, and, as has sometimes happened, the introduction 
of a definite name for a thing previously talked about onlv 
in general terms has promoted its consideration: — witness the 
name, antecedent, for rivers that hold their courses against 
mountains uplifted beneath them. The idea of antecedent 
rivers had occurred to several observers who gave it no name, 
and unnamed it gained no general currency; but it became 
popular when Powell named it. Moreover, the ideas of ante- 
cedence and peneplanation were ripe in many minds about 
the time the names were suggested, and it is chiefly for that 
