. 
450 J. LeConte— Formation of the Earth-surface. 
not the fact itself, but the wse of the fact in sustaining my 
theory. All I claim here, therefore, is the connection of this 
fact with the position and formation of mountain chains. 
5. I attribute the enormous /oldings of the strata of mountain 
chains to horizontal crushing together, produced by the interior 
contraction of the earth. Mr. Hunt makes reclamation of 
this also. Let us compare our views on.this subject. Mr. 
Hunt attributes the folding of the Appalachian chain to three 
causes ; (a) Subsidence of a convex mass of sediments; (this I 
have shown (p. 461) could not take place if the sedimentation 
and the subsidence went on pari passu. (6) Contraction of the 
strata by metamorphism ; (this I suppose could only produce 
foldings by producing subsidence of the convex surface, and 
myself as well as by others; that neither he nor Hall ever pro- 
posed any theory of mountain formations at all, but only a re- 
turn to the views of Buffon and Montlosier, that “ mountains 
are fragments of denuded continents.” ‘ 
In order to make my explanation of this point clear, I find it 
necessary to define my terms. The word mountain 1s y 
_ used, in scientific as well as in popular language, to express 
every considerable inequality of the earth surface, from a Seer 
mountain chain like the rete or the Himalayas, to mere ills 
 circumdenudation like those on the upper Mississipp!- The 
