214 
NATURE FOR ITS OWN SAKE 
How 
mountains 
are formed. 
The Alps. 
ridge is a bulge or break in the dome of ma- 
sonry, and not a string-course where an extra 
layer of rock is placed for ornament or strength. 
It seems to be the present scientific conclu- 
sion that mountains are not formed so much by 
voleanic action as by the folds or laps in the 
crust made by the contraction of the earth as it 
grows older and colder. The illustration used 
is that of the skin or surface of an apple. It 
wrinkles in folds as the apple withers and de- 
creases in size; and these folds in the skin of 
the apple correspond to the mountains and val- 
leys of our earth. The illustration and the 
conclusion are both very plausible. The long 
line of the Rockies once lay, perhaps, thousands 
of feet beneath the flat bed of an inland sea, but 
some contraction of the earth, some great sink- 
ing-in of the crust on either side, caused a cor- 
responding fold to rise, and the result was the 
long range of mountains from Alaska to Pata- 
gonia. The high point of the fold came just 
on the central line of the ridge, and from that 
outward, on either side, this fold was less 
marked, producing near at hand the smaller 
spurs, then the slightly heaved foot-hills, 
finally merging into the undisturbed plains. 
The Alps were doubtless formed in a similar 
