THE HISTORY OF THE GROUND. 21 



winter's ice left just ready to fall. Perhaps in this way 

 the great lump that cut down the tree not many weeks 

 ago was toppled over. The wind may also in storms 

 brush off small bits already loosened and ready to fall, 

 and occasionally the lightning splits off a fragment. 

 Every rain that falls brings down acids from the air to 

 slowly eat away the rock. The sun warms the face of 

 the rock, and helps to destroy it by expanding its 

 surface, and opening minute channels for the sudden 

 summer rain, that with thin fingers seeks out every 

 crack to pull the rock to pieces. Even the mosses 

 and lichens growing here and there, and the roots of 

 trees and plants, assist in the work ; and thus the noble 

 cliff reared so high in the air, even the mountain itself, 

 is visibly falling in ruins before our eyes. Slowly, in- 

 finitely slowly, but without pause, the work goes on, 

 and has gone on since that wild day when with frightful 

 sounds and awful earthquakes, old Schunemunk was 

 upraised. As we go down the mountain-side, we find 

 again the fragments of trap-rock. There, too, are the 

 ruins of some higher cliff. It is a harder rock, and the 

 pieces are sharp and jagged. The weather must have 

 worked very slowly, for the edges and corners are 

 hardly dulled. The trees that spring up among the 

 stones show they have lain here for at least fifty years, 

 and the stones are almost unchanged in that time. 

 The years that passed while they were slowly broken 

 down from their old cliff may be numbered by hun- 

 dreds. No man can tell. We can only observe that 

 while the work now going on at the pudding-stone 



