and on the Age of the Cascade Mountains. 179 
b 
horizontally and an up-swelling spices of lines of thick sedi- 
Jorce which elevated the mountain ranges ; by enormous horizontal 
pressure, determined by the interior contraction of the whole 
ard, steam generate meteoric waters perco- 
and the amount of fissurings and fissure-eruptions on the other. 
This I believe to be a true principle. I wish, therefore, to illus- 
trate and explain it. 
Mountain ranges are first formed as already explained. But 
the ranges thus first formed, usually become afterward lines of 
successive elevation by lateral pressure. A mountain range, first 
born of th 
trary, the subsequent yielding of the already hardened land- 
Surface takes shins only after much resistance, and, therefore, 
with much heat, even to fusion of the strata, and also paroxysm- 
ally, with the fissuring of the strata and the out-squeezing of the 
whole extent of the height of the mountain: while in the sec- 
ond case, the increase i . 
vi, pelts of Karth's Contraction—part 4, Igneous Hjections. This Journal, vol. 
