FUTURE OF THE EARTH. 307 



cooling of our planet causes the thin crust already 

 foruiel, by unequal contraction, to pucker up. The 

 sea occupies the cavities — tlie prominences alone 

 appear above the waters. 



Water tends to combine more and more with the 

 rocks. A time will probably come when the earth 

 will be too cold for water to exist in the liquid state. 

 It is to be understood, in fact, that the quantity of 

 water which bathes our planet continually diminishes ; 

 but this diminution is so slow, that thousands (»f 

 years are not sufficient to make it evident. 



