THE PENEPLAIN—A REVIEW. 
R. A. DALY. 
ALL workers in Physical Geography are agreed that, given 
time enough and a constant position of the baselevel, the gen- 
eral processes of denudation on the land will produce, as the 
result of wearing down any massif, a nearly plane surface ap- 
proximately coincident with the baselevel of the region. Pro- 
fessor Davis and his followers believe that this ideal condition 
is represented by actual examples in nature, examples which 
deviate from the ideal in features that are the expected con- 
comitants of even long-continued denudation. Chief among 
these is the occurrence of isolated areas of higher ground than 
the general plain, existent as such because of greater initial 
elevation of those parts of the massif or because of their being 
composed of exceptionally hard rocks; they are the ‘ monad- 
nocks” dominating the otherwise nearly featureless plain. 
That, in such a case, we have to do with an almost-plain, a 
peneplain, is regarded as none the less certain on account of 
the presence of these residual hills; on the contrary, they fur- 
nish one of the strongest arguments for the fact of denudation. 
The nearly plane surface of the rest of the massif can be quite 
independently recognized in the field and on the map. In a 
recent number of the American Geologist! Professor Tarr 
states his opinion that, while conceding the possibility of pene- 
plains on an ideal planet, they do not exist, have not existed, 
and, if I understand him aright, can not exist on this earth of 
shifting baselevels, moving up and down within time limits 
represented by one or more geological periods. 
Professor Tarr’s arguments against the theory of peneplains 
are both general and special. In the former category are the 
following : (1) The theory is faulty because it demands too 
much time. (2) Closely correlated therewith is the objection 
1 June, 1898. 
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