No. 386.] THE PENEPLAIN. 137 
about ; but, by all the laws of analogy, it is simplest to believe 
that the same explanation of differential hardness applies here. 
(I would go so far as to say that, on the basis of direct observa- 
tion in the field, it is not differential e/evation that explains the 
existence of Mount Monadnock.) 
Following his criticism of the peneplain theory, Professor 
Tarr attempts some constructive theorizing on the present relief 
of such regions as New England and New Jersey. He regards 
it in each case as a mountainous area in the condition of “full 
maturity of topography,” “reduced mountains, lowered to the 
stage of full maturity.” “By this explanation it is held that 
the region was never reduced to the peneplain stage, but has 
always been, as it still is, a mountainous section, though once 
less mountainous than now, because of the recent uplift.”” But, 
disregarding the uplift, is it correct to speak of such relief as’ 
that of Massachusetts as characterized by a stage of “mature” 
dissection? Will the average inhabitant of the upland be flat- 
tered in learning that the tract in which he lives ought, by the 
laws of distribution, to be occupied by a few miserable, impov- 
erished individuals, isolated by a labyrinth of valleys and hills 
from their fellows? For such is the condition of most of the 
maturely dissected areas of the earth’s surface; the moon- 
> 
shiners of West Virginia eloquently represent one result of 
mature dissection. Fortunately for the needs of man, a ma- 
turely dissected region is almost as rare as one that is char- 
acterized by chronic earthquakes of destructive violence. But 
when, in addition, Professor Tarr states that, by “mature” 
topography he did not mean even the present relief, but a 
topography made “more rugged” by the recent uplift, it is all 
the more difficult to subscribe to his nomenclature of that ear- 
lier surface. So far is the Berkshire plateau, for example, from 
being of “mature ” form, made more rugged by uplift, that an 
unprofessional observer, returning from a walking tour across 
the plateau, has remarked to me in very definite language 
that the plateau is “flat,” so strong was the impression upon 
him of the even-topped character of the whole. Yet how likely 
is the untrained student of land-forms to overlook the existence 
of a topographic facet, however faintly it may be dissected! 
