Twenty Hiill Hollow 
of those convenient tools demanded for the 
making of mountain Yosemites, and our mod- 
erate arithmetical standards are not outraged 
by a single magnitude of this simple, compre- 
hensible hollow. 
The present rate of denudation of this portion 
of the plain seems to be about one tenth of an 
inch per year. This approximation is based 
upon observations made upon stream-banks 
and perennial plants. Rains and winds remove 
mountains without disturbing their plant or 
animal inhabitants. Hovering petrels, the fishes 
and floating plants of ocean, sink and rise in 
beautiful rhythm with its waves; and, in like 
manner, the birds and plants of the plain sink 
and rise with these waves of land, the only dif- 
ference being that the fluctuations are more 
rapid in the one case than in the other. 
In March and April the bottom of the Hol- 
low and every one of its hills are smoothly 
covered and plushed with yellow and purple 
flowers, the yellow predominating. They are 
mostly social Composite, with a few claytonias, 
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