84 SEA AND LAND 



^vhich exceed fifteen thousand feet in height, and some score 

 wliich rise twenty thousand feet above the sea level. There 

 are indeed several considerable areas of mountainous country 

 where extensive fields attain a greater height than the aver- 

 age depth of the sea. It is thus at once plain that if moun- 

 tains developed in the ocean-floor as freely as they do on the 

 land there would be a great number of them rising above the 

 plane of the seas, but in fact that there is not a single dis- 

 tinct mountain peak rising above the water level at any great 

 distance away from the margins of the continents. All the 

 numerous islands of the wide oceans are either coral reefs or 

 the summits of volcanic cones. 



It is furthermore evident that if mountains grew upward 

 from the sea-floor they would attain the surface of the water 

 without being subjected to the erosion which has robbed the 

 elevations of the land of a great part of their height. If we 

 carefully examine any of the great mountainous peaks of the 

 continents we find that they have been much worn away by 

 the rivers, torrents, frost, or glaciers, which have always oper- 

 ated uj)on them ; but mountains growling upon the sea-floor 

 would be safe from these assaults until they rose above the 

 surface of the water. We would on this account expect to 

 find them even more abundant and of loftier forms in the 

 marine areas than on the parts of the earth's surface which 

 rise above the sea. We are therefore forced to the conclu- 

 sion that mountains do not form upon the sea-floor, or if they 

 develop there they attain no such dimensions as they exhibit 

 upon the land. 



Although the deeper sea-floors probably lack mountains, 

 they are not without striking reliefs which if they could be 

 seen would present all the dignity which their height gives to 



