4 8 



COMMON PHENOMENA DUE TO HEAT 



While most of us are familiar with the bursting of water 

 pipes on a cold night, few of us realize the influence which 

 freezing water exerts on the character of the land around us. 



Water sinks into the ground and, on the approach of winter, 

 freezes, expanding about one tenth of its volume; the expand- 

 ing ice pushes the earth aside, the force in some cases being 

 sufficient to dislodge even huge rocks. In the early days in 

 New England it was said by the farmers that " rocks grew," 

 because fields cleared of stones in the fall became rock covered 

 with the approach of spring; the rocks and stones hidden 

 underground and unseen in the fall were forced to the surface 

 by the winter's expansion. We have all seen fence posts and 

 bricks pushed out of place because of the heaving of the soil 

 beneath them. Often householders must re-lay their pave- 

 ments and walks because of 

 the damage done by freez- 

 ing water. 



The most conspicuous 

 effect of the expansive 

 power of freezing water is 

 seen in rocky or moun- 

 tainous regions (Fig. 25)- 

 Water easily finds entrance 

 into cracks and crevices 

 of rocks, where it lodges 

 until frozen; then it ex- 

 pands and acts like a wedge, 

 widening cracks, chiseling 

 off edges, and even breaking 

 rocks asunder. In regions 

 where frequent frosts occur, 

 the destructive action of 

 water works constant changes in the appearance of the land. 



FIG. 25. The destruction caused by 

 freezing water. 



