MOUNTAINS 327 
some part to rise in order that the rest might settle. 
This rismg would then have the appearance of a 
thrust from one side; for the necessity of sinking 
in one part would push up a neighboring portion. 
Naturally, this uplifted part would often be in the 
vicinity of the shore, for this line is near the place 
of weakness, where uplift is most frequent; that is, 
near a more ancient line of folding. 
This theory also explains the slowness of folding ; for 
of course, the contraction cannot be such as to produce 
rapid uplift. A local stretching, like that seen in the 
Great Basin, may merely be a broad upfold, which at 
this place is bemg stretched, while elsewhere, in other 
parts of the same fold, the rocks are beg pushed 
horizontally.’ 
So it seems, that while objections are urged on more 
or less theoretical grounds, the contraction theory ex- 
plains the main facts of mountain growth; and against 
it there can be fewer objections urged than against any 
other. Therefore, while it may not be the true expla- 
nation, it seems the most reasonable suggestion yet 
offered; and in this respect, compares favorably with 
many other attempts which man is making to account 
for the phenomena of nature. 
1 The crest or ridge of an anticline, or any upfold of this kind, is a place 
of stretching ; the base of the fold, or the syncline is a place of pressing. 
This can be proved by pushing a piece of stiff wax-covered cardboard into 
anticlines and synclines. 
