THE HISTORY OF THE GROUND. 19 



we reach it we find a mass of rusty rock has plunged 

 completely through it. Climbing as best we can over 

 the wild confusion of smashed and broken rocks and 

 shattered trees, we reach the base of the gray cliff. 

 It is split and splintered in every direction, and many 

 pieces seem ready to fall and crush us. It is evident 

 this cliff is being torn down, for here are the fragments 

 at our feet. The work is going on now, for the fallen 

 tree was cut down this very summer. The leaves have 

 only withered recently, and the splintered wood is still 

 fresh. The cliff is fast weathering away. 



What are the causes of this destruction ? Is it best 

 that this great Schunemunk Mountain be thus torn 

 down? and what good will come of all this ruin- 

 ous change ? We pick up a mass of pudding-stone, 

 and throw it down upon the rocks below, and it bursts 

 into a thousand pieces, and a shower of pebbles rat- 

 tles over the rocks. Observe the color of the stone, 

 a dull red. The plums of the pudding-stone are 

 bound together with iron. It has rusted on exposure 

 to the air, and falls apart easily. Here is our first clew. 

 The air is at work on the cliff. The oxygen of the air 

 is combining with the iron to form the red dust called 

 oxide of iron, and the pebbles being bound only with 

 dust easily fall apart. Here we see the air is an 

 agent in breaking down the rocks. The gases in the 

 air act chemically upon all rocks, to disintegrate and 

 break them up into dust and powder. So it has been 

 since the first rocks appeared. The moment they 

 were exposed to the air, they began to be destroyed. 



