TIME AND CHANGE 
ward one upon the other.” In northern Montana 
there is an over-thrust of the Cambrian rocks upon 
the late Cretaceous, of seven or eight miles, carry- 
ing with it what is now called “Chief Mountain,” 
which has been carved out of the extreme end of the 
over-thrust. The contemplation of such things gives 
one a sense of power in Nature beyond anything else 
I know of. The shrinking of the globe as a whole 
makes its rocky garment too big for it, and this 
titanic wrinkling and folding results. When the 
strata snap asunder under the strain, we have earth- 
quakes. During the recent San Francisco earth- 
quake, Mount Tamalpais, across the bay, and all 
the neighboring heights, were permanently shifted 
eight or ten feet. The sides of the mountain, it is 
said, undulated like a curtain. And this shaking 
and twitching of the great rocky skin of the earth 
was vastly less, in proportion to the size of the globe, 
than the twitching and trembling of the skin of a 
horse when he would shake off the flies, in compari- 
son with the animal’s body. 
We see another exhibition of the magnitude of the 
earth’s forces in what the geologist calls a “‘lacco- 
lite’? — a great cave or cistern deep beneath the 
surface of stratified rock filled with hardened lava. 
The lava is forced up from an unknown depth under 
such pressure that, not finding an outlet at the sur- 
face, the rock strata, hundreds or thousands of feet 
thick, are lifted up and arched like so much paper, 
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