THE 



Ho. XXIY.— JUNE, 181 



OI^T(3-IIs^.A.ZJ Jk-I^TICLIES. 



I. — On the Origin of Hills and Valleys.^ 

 By G. PouLBTT ScROPE, Esq., M.P., F.R.S., F.G.S., etc. 



WHILE referring the present "form of the ground," in a large 

 degree, to the several agencies of atmospheric and marine denu- 

 dation, do not let us ignore the, at least, equally efficacious action of 

 subterranean force. This Professor Jukes appears to me to do, to 

 an extent likely to mislead ordinary readers, naturally influenced by 

 his high authority, in the communication from him published in 

 your last number (Vol. III. p. 232). He there speaks of "the action 

 of internal forces," as "having no direct efiect on the external 

 features of the ground." In a subsequent sentence, indeed, he makes 

 exception, in a parenthesis, of "volcanic cones and craters," but seems 

 to . consider these exceptional cases as of trifling moment, and to 

 deny altogether the influence of other internal forces in producing 

 superficial elevations or depresssions. 



Now, in the first place, I would observe that the admitted excep- 

 tions compose in the aggregate no trifling proportion of the moun- 

 tainous excrescences of the globe's surface, including, among others, 

 the bulk of the entire chain of the Aaides and Cordilleras of South 

 and North America, the mountain masses of 'Iceland, Etna, Ararat, 

 Teneriffe, Kamschatka, Java, Sumatra, etc., with all those numerous 

 volcanic islands of the Pacific and Atlantic, which are in fact sub- 

 marine mountains, stretching their roots to great depths in the 

 ocean valleys around. But besides this enormous amount of elevated 

 surface falling within the Professor's parenthetical exception of vol- 

 canic cones, are we to overlook the effects of those other subter- 

 ranean forces, indicated to external perception in all probability by 

 earthquake-shocks, and quite distinct from the outpouring of matter 

 from volcanic orifices, by which the superficial rocks have evidently 

 been, tlu-ough all time, in some places elevated, in others depressed ? 

 No one, more readily than myself, will join with Professor Jukes, 

 in deriding what he calls " the hocus-pocus of grand convulsions, by 

 which mountain chains were (and, perhaps, still are, by some geo- 

 logical schools) believed to have jumped (at once) out of the interior 



1 See the May Number, page 193. 



VOL. III. NO. XXIV. 16 



