in the Geological History of North America. 337 



peak near the equator is 20,000 feet. In Australia, the Austra- 

 lian Alps, as they are called, are on the east fronting the Pacific, 

 here the wider of the bordering oceans. 



Thus all over the world, the highest mountains stand fronting 

 the largest and deepest oceans ; and the " rule of three" state- 

 ment of the fact scarcely conveys a wrong impression. 



2. We observe further that the coasts are in general so turned 

 as to face the widest range of ocean. The Appalachians with 

 the neighboring coast do not face northeast towards the Euro- 

 pean continent, but southeast, towards the great opening of the 

 Atlantic between America and Africa. So on the west side of 

 North America the Pacific coast faces, not towards Asia, but 

 southwest, where the broadest range of ocean is before it. 



3. Consider now a little more closely the structure of these 

 ocean borders. How is it as to the effects of heat or volcanic 

 action ? 



In North America, on the side of the small ocean, the Atlantic, 

 we find metamorphic rocks, some trap dykes, and a few tepid 

 springs. On the side of the great ocean, the Pacific, all these 

 phenomena occur, and besides, some of the grandest volcanoes 

 of the globe, while basaltic floods have buried out of sight 

 almost all other rocks over a considerable part of the country. 

 Mount St. Helens, Mount Hood, Mount Shasta, and a dozen 

 others, twelve to eighteen thousand feet high, make a majestic 

 file of fire mountains not yet wholly extinct. May we not then 

 say, As the size of the Atlantic to the action of heat on the Atlantic 

 border, so is the size of the Pacific to the action of heat on the Pacific 

 border ? 



In South America, there is a direct repetition of the same facts 

 on a still grander scale : the Brazilian side, with metamorphic 

 rocks and no volcanoes ; the Pacific side, with volcanic heights 

 of 20,000 feet and upward. 



In the Orient, there are some small volcanic operations on the 

 Atlantic side ; but an unnumbered host down through Kamt- 

 schatka, Japan, and the islands south on the Pacific side. 



In Africa, there are great volcanoes in the Eed Sea and the 

 lofty Abyssinian mountains, and only a few on the east, in the 

 Gulf of Guinea, where, in fact, the continent opens on the South- 

 ern Ocean and not simply on the narrow Atlantic ; the volca- 

 noes are at the junction of the two lines, in or near the Bight of 

 Biafra. 



4. Again, these effects of heat are confined mostly to the re- 

 gion between the crest of the border mountains and the ocean, 

 and are most intense towards the coast line. Thus the crystal- 

 lization or metamorphism of Eastern North America, from Lab- 

 rador to Georgia, is strongly marked towards the ocean, and 

 diminishes going westward. So on the Pacific side : the great 



SECOND SERIES, VOL. XXII. NO. 66.-N0V., 1856. 



43 



