Tlie Peneplain. — Davis. 235 
the mountains are then under essentially uniform climatic con- 
ditions, and for the rest of their lives difference of structure 
will determine their rate of decay. All changes would truly ; 
be very slow, but small differences in rate of wasting would ' 
suffice to develop distinct dififerences of altitude while the \ 
mountains were worn down from the tree line to the farm ! , 
line. The uneven hill and mountain districts about lake Win^/ 
nipiseogee, X. H., might be evolved in this way; but it se^ms 
to me very doubtful whether any such equality of hight as 
prevails in central Massachusetts can be explained ^s an in- 
heritance from an equality determined by climatic control 
when the region had a much greater elevation, for to-day these 
uplands are about 3000 feet below the tree line, and their 
structure is by no means uniform. 
C 3. The beveling of hill tops. It is said that "by the time v 
maturity of topographic form has been reached, there will be 
a beveling of hill tops where the harder gneissic and gran- 
itic rocks exist" (p. 368). I am not sure whether this and 
other references to beveling are correctly interpreted in what 
here follows, but the intended meaning seems to be that the 
hill tops would be somewhat flattened so as to imitate the 
broad uplands that are often found in (so-called) uplifted and 
dissected peneplains. That is, the conical form, FJK, would 
be changed to the beveled or truncated form, FV^WK. Eev- J^) ' 
eled forms of this kind are certainly common in central and ' 
western Massachusetts and in northern New Jersey; they are 
much better developed in such districts as the Piedmont belt 
of Virginia, the western part of the central plateau of France, 
and the uplands of the Slate mountains in western Germany. 
The broadjy beveled upland, FMNK, would represent the 
type form in some of these examples. Not only are the an- 
cient mountains beveled, but their beveled uplands fall in a 
systematic and accordant manner closely into a single plane, 
usually an inclined plane. There can be no question of the : 
fact of such beveling, so far as existing form is concerned, in \ 
many well preserved peneplains; but no sufficient explanation \ 
of the process of beveling is given in Professor Tarr's article. 
It is briefly asserted. An explanation would be hard to find. ; 
unless it involved someespecially active process. a function of 1 
altitude and climate, such as Richtcr has suggested for the 
