CHAPTEK II. 
THE EARTH-BOOK. 
In the preceding volume I have considered the 
river valley and how the water made it; how the 
contraction of the earth’s crust on account of the 
radiation of heat has produced elevations and cor¬ 
responding depressions; how heat by liquefying the 
subterranean materials has thrown up volcanoes; 
how water percolating through rock strata, forming 
springs and underground rivers, has carved out cav¬ 
erns, carried the debris together with that eroded on 
the surface to the sea, and there deposited it; how 
plants and animal forms were buried in these deposits 
and preserved as fossils to become the key in retra¬ 
cing the history of the world; how animal and plant 
life contributed their share in making the great lay¬ 
ers of limestone and coal; and how wind and sea, 
and heat and life, are still carrying forward earth’s 
faithful record. 
Let us now together turn over the great leaves of 
the earth-book and see if we can decipher some of its 
significant hieroglyphics. I am sure they reveal a 
wonderful story of life and death, of struggle for 
existence and ‘‘ survival of the fittest.” 
As we have already studied the alphabet which 
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