368 The America)! Geologist. p, ii^9s 
the difference in rate of downwearing would even i ^jidly 
diminish as soon as a soil covering became possi .c. in the 
meantime, a higher or more durable neighbor might still be 
sinking more rapidly, and, in time, might almost catch up with 
a more favorably situated and lower peak. The curves of the 
rate of denudation in the two cases would approach and 
finally almost coincide; and, unless the rock differences were 
marked, the two peaks would proceed to be lowered at about 
the same rate. If the rock differences were very marked, there 
would be no exact approach; but, according to this view of 
the method of denudation, even though there was originally a 
marked difference in altitude, all peaks whose rocks were ap- 
proximately the same in power of resistance would in time 
approach each other in altitude, the one originally higher 
catching up with the other whose rate of lowering was becom- 
ing rapidly diminished because of decreased elevation. It 
must be granted that in such a mountainous country as that 
of New; England down below the surface there are extensive 
beds of rock of approximately the same hardness. That this 
is so is proved by the abundance of durable gneiss and granite 
in most low mountainous areas, as for instance in New Eng- 
land and New Jersey. 
By this there would be a beveling of the hill tops, the 
highest area of beveling being that part of the tree zone in 
which, because of lessened slope, the rock was protected by 
trees and by a residual soil blanket. Down to this zone de- 
nudation would be relatively rapid, below it much slower, and 
increasingly slower as the beveling continued still further. In 
a mature mountain region so developed there would be some 
peaks not yetJowered to this area, and there would be great val- 
leys depressed below it. But would it be incorrect to assume 
that in a given area where most lowered, from lo to 25 per 
cent of the reduced mountain tops would probably have 
reached a fair uniformity of level? This beveling of the hill 
tops would be very much further advanced near the coast 
than in the interior, thus coinciding with the conditions found 
in New England.- 
According to this view, by the time maturity of topograph- 
ic form has been reached, there will be a beveling of hill tops 
where the harder gneissic and granitic rock exists, the stream 
