TUB EARTH FRAME 



199 



earth. If it were not for them there would be 

 more Saharas of desolation, and the green of 

 the earth in many a tract now lovely in light 

 and color, would take wings and vanish into 

 space. It is color that gives the glow of life to 

 the earth, and yet this great beauty might dis- 

 appear without weakening in any way the frame 

 or form of the globe. The earth could and 

 would exist, and swing on in its orbit, were 

 there no life, no light, no color upon it. The 

 modelling of the mountains, the deep-incised 

 river valleys, the flat spaces of the plains, the 

 hollow depths of the ocean-beds, would remain 

 substantially as to-day. For the material of 

 which the earth is formed is so cohesive that 

 its shape would probably hold for centuries 

 after its seas had evaporated and its atmos- 

 phere had passed away. The interior of the 

 globe may be fire or rolling vapors, or simply 

 solid matter ; man speculates about it without 

 absolute knowledge. But about the crust he is 

 quite certain that it is rock formation, made 

 in different ways and at different geological 

 periods of the earth's history. 



Doubtless, the whole globe was at one time 

 covered with sea, and when the waters receded 

 from the table-lands there was a hardening of 



The earth' t 

 skeleton. 



Itsttrength. 



