THE PROBABLE FUTURE OF THE HUMAN RACE. 145 



example that of worn iron, which is everywhere scattered on the earth, 

 will be much more difficult to obtain than the primitive accumulations 

 of to-day. There must be necessarily a diminution of population as 

 these essential resources become rare and more and more inaccessible, 

 until finally they are quite exhausted. The people will then be in a 

 most unhappy condition. There will be no railroads, no steamboats, 

 nothing which requires coal or metal. Their industries will gradually 

 be reduced as copper and iron become scarce. Certain populations at 

 once sedentary and agricultural, living in the warm countries and able 

 to content themselves with little, will then be the best adapted to the 

 general circumstances of the globe. At the tropics, therefore, and in 

 the vicinity of the great accumulations of coal in the United States, 

 populations will remain longest collected in masses. The rarity of the 

 metals, however, will be a cause of decadence, even in these privileged 

 localities. 



Another change, slower but equally sure, is the diminution of terres- 

 trial surfaces, and particularly the lowering of elevated regions, by the 

 incessant action of water, of ice, and of air. For thousands of years, 

 every stream, every river, has carried toward the ocean solid particles 

 detached from these heights, and this slow process must continue. The 

 mean lowering of continents has been calculated from the ooze of the 

 principal rivers, supposing proportions to be constant. Such calcula- 

 tions, however, rest upon conditions too variable to merit much confi- 

 dence ; but the tendency of the change is certain. Upon high mountains 

 and in the polar regions, glaciers corrode the hardest rocks and carry 

 solid substances to the rivers. Less elevated surfaces are in like man- 

 ner depressed by the action of water. The ooze is finally transferred to 

 the bottom of the seas ; and as the latter have already an extent much 

 greater than the land and a depth surpassing the elevation of the high- 

 est mountains, it is clear that the solid land habitable by man will dimin- 

 ish relatively to the liquid surface. In other words, the bottom of the 

 seas is filling up in part and the surface must rise more or less, if we 

 suppose the liquid mass constant. At the same time, for several centu- 

 ries the additions to certain coasts may be considered equal to the ero- 

 sions of others, and partial elevations counteracted by equal depressions. 



Thus, independent of abnormal events, which it is impossible to fore- 

 see, all existing phenomena indicate that the islands and continents 

 must first diminish in elevation, then in extent, and we may predict that 

 in some far distant future a very nearly complete submersion of terres- 

 trial surfaces will take place, and consequently a destruction more or less 

 complete of all organized beings, vegetable and animal, which live upon 

 these surfaces, or even in fresh waters. The human species, on account 

 of superior intelligence, may survive longer than the others ; but they 

 also will then be near their end, since they will be able to live only upon 

 boats, and there will be neither wood nor metal of which these can be 

 constructed. The submersion of continents will probably not be general, 

 S. Mis. 115 10 



