338 



/. D. Dana on the Plan of Development 



volcanoes are not on the east or landward side of the crest, for 

 there is not a volcano on that side, but on the seaward side, and 

 not very far from the ocean. Thus we may almost say, The 

 nearer the water, the hotter the fire. 



5. Again, the mountains that make the borders, consist as is 

 now well known since the surveys of the Professors Kogers, of 

 rocks that have been pressed up out of place into a series of 

 immense folds, like the folds we may make in paper by press- 

 ing laterally ; only the rocky folds are many miles in range and 

 of mountain height ; and these folds or plications and displace- 

 ments are most numerous towards the ocean, and are parallel 

 nearly to the ocean. Hence again, The nearer the water, the vaster 

 the plications of the rocks. 



6. Over the interior of North America, there are not only no 

 volcanoes, but there never have been any since the earlier Silu- 

 rian, as shown by the absence of their remains among the strata ; 

 and this is so, notwithstanding the abundance of salt water over 

 the regions in those ancient times. Over the interior of Asia 

 there are no volcanoes, as is well known, except the three or four 

 in the Thian-Chan Mountains. The great volcanic belt of the 

 Orient stands out a short distance from the water-line of Asia, 

 in the Japan range of islands, thus directly edging the oceanic 

 basin ; for the intervening region of shallow waters is properly 

 a submerged part of the continent. 



7. In contrast with this non-volcanic character of the interior 

 of the continents, the islands of the oceans, it should be remem- 

 bered, are all volcanic where not coral, and those of coral proba- 

 bly rest on a volcanic basis. Dhwalagiri, in the Himalayas, 

 28,000 feet high, is granitic ; and surely we might have looked 

 for some granitic peaks among the central islands of the oceans : 

 but there are none. 



At the same time, as others have remarked, the transverse 

 seas which divide the Northern and Southern continents, the Bast 

 Indies, the Mediteranean and West Indies, are characterized by 

 volcanoes. 



If then, the typical form* of a continent is a trough or basin, 

 the oceanic borders being raised into mountains ; if these borders 

 are so turned as to face the widest range of ocean ; if the height 

 of these border mountains and the extent of igneous action along 

 them is directly proportioned to the size of the oceans, — the Pa- 

 cific, accordingly, being girt with great volcanoes and lofty moun- 

 tains, while the narrow Atlantic is bounded by smaller heights 

 and but few volcanoes ; if, moreover, volcanoes characterize the 

 islands of mid-ocean and not the interior of the continents : What 

 is the legitimate inference ? 



Most plainly, that the extent and positions of the oceanic de- 

 pressions have some way determined, in a great degree, the fea- 



