THE FRIENDLY ROCKS 
issued from the rocks a few yards away, and set 
upon a little shelf as if it had grown there. There 
was a hole on one side that led to the soft and warm 
interior, but when my forefinger called, the tiny 
aristocrat was not in. Whether he or she belonged 
to the tribe of the white-footed mouse, or to that of 
the jumping mouse, I could not tell. Was the de- 
vice of the mossy exterior learned from the phoebe? 
Of course not; both had been to the same great 
school of Dame Nature. 
Through the eyes of the geologist I see what the 
agents of erosion have done, how the tooth of time 
has eaten out the layers of the soft old red sand- 
stone, and left the harder layers of the superimposed 
Catskill rock to project unsupported many feet. I 
see these soft red layers running through under the 
mountains from valley to valley, level as a floor, 
and lending themselves to the formation of the beau- 
tiful waterfalls that are found here and there in the 
trout brooks of that region. At one such waterfall, 
a mile or more from the old schoolhouse, we used to 
go, when I was a boy, for our slate pencils, looking 
for the softer green streaks in the crumbling slaty 
sandstone, and trying them on our teeth to see 
whether or not they were likely to scratch our pre- 
cious slates. In imagination I follow this slaty layer 
through under the mountains and see where it is cut 
into by other waterfalls that I know, ten, twenty, 
thirty miles away. At those falls the water usually 
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