26 THE WORLD'S LUMBER ROOM. 



besides admitting water into these cracks, most rocks also 

 absorb more or less, according to their texture and composi- 

 tion. One coarse kind of granite, for instance, has been 

 found to suck up as much as four pounds of water to the 

 cubic foot in the course of eighty-eight hours, when kept 

 entirely submerged ; and although rocks are seldom so 

 severely tried as this in Nature, they must take up a certain 

 amount of water in one way or the other, and when this 

 remains sufficiently near the surface to be frozen, every 

 single drop of it expands with such force as to splinter the 

 surface and widen the cracks within, thus affording easier 

 entrance to the rain on the next shower. 



The cliffs along the Hudson River are piled up to more 

 than half their own height with the immense heaps of frag- 

 ments which have been detached in this way, the winters 

 in the State of New York being so severe that the frost 

 penetrates to a great depth below the surface. 



High up among the mountains this work of destruction 

 goes on, not in the winter only, but almost daily throughout 

 the year, the scorching heat of noon, which melts the ice and 

 snow, withers the grass, and blisters the face, being often 

 followed by sharp frost at night. And the result of these 

 extreme and constantly-repeated changes is, not only that 

 the mountains are cut and carved into such bold pinnacles 

 as are seen around Mont Blanc, but that many an appa- 

 rently solid ridge of rock is found, on inspection, to consist 

 of large angular fragments, still in the position they occu- 

 pied when united, but so loosely piled together that a gust 

 of wind might scatter them. 



Even in Great Britain the wreckage produced simply by 



