THE REVOLUTIONS OF THE CRUST OF THE EARTH 347 



nearly with the time when the excess in the number of the days of sum- 

 mer and of autumn commenced to diminish. 



If we admit that the precession of the equinoxes embraces a period 

 of 21,000 years, then for 10,500 years the seasons will be reversed by 

 relation to the perihelion. Our hemisphere will then be cooling during 

 9,779 years, the period of maximum cold, after which its temperature 

 will gradually increase until the maximum of heat. 



M. Adn6mar, iu his remarkable work published in 1842, has endeavored 

 to connect this periodicity of the return of the extremes of cold and of 

 heat with the periodical return of the waters upon the continents. He 

 has attempted to prove that the idea of a universal deluge is justified 

 by the facts of science. He brings forward some very just considera- 

 tions to show that the periodical return of the waters is a very general 

 phenomenon which cannot be attributed to any local cause, such as, for 

 example, the irruption of the sea into a continental depression. The 

 almost universal traditions of a deluge with the inhabitants of both con- 

 tinents cannot be attributed to a common source, for they are found not 

 •only with the Semitic races, but with the Basques, the Celts, the Hindus, 

 the Mongols, and many African tribes. In America, especially, these 

 traditions are numerous and very varied, and often remarkable in their 

 coincidence with that of the Hebrews. Some races speak of several 

 deluges, but the greatest number mention only one. As to the extent 

 of the deluge the traditions vary. Sometimes it is a tribe, sometimes a 

 family, then all humanity which was destroyed, with the exception of a 

 single family or one couple saved on the trunk of a tree, on an arch, or 

 on the top of a mountain.* 



The masses of bones found upon the hills and banks of Siberia equally 

 prove that animals were overtaken and engulfed by the waters, and 

 were covered with mud and sand. A proof has also been found in sup- 

 port of Mr. Adh6mar's view in the erosion of entire deposits such as 

 could have been produced only by currents of great rapidity. It has been 

 ascertained also, through researches made in Canada, that these currents 

 were directed principally from north to south. The periodic return of 

 the waters has produced in the basins subjected to it alternate fresh 

 and marine water. 



If we examine attentively the unequal distribution of the continents 

 on the surface of the globe, their form pointed toward the south, the 

 depth of the austral seas which is at least three times that of the boreal 

 seas, we must acknowledge that the position of the waters which cover 

 the earth in relation to the solid portions is eccentric, and can be explained 

 only by an unequal density of the different parts of the terrestrial mass, or 

 rather by the existence of a solid mass upon the austral pole, which by 

 its elevation produces a displacement of the center of gravity of the 

 earth, and consequently changes the level of the sea. 



The solid mass which, according to Mr. Adh6mar, produces this dis- 

 * Fr. Troyon, V Homme fossile, 1867, p. 140. 



