WINTER EARTH STUDY. 513 



THE WORK OF WATER IN SOIL-MAKING. 



This topic forms an excellent transition to the spring 

 plant work, a preparation for the observation of the work 

 of rain and running water and an introduction to real 

 earth study, or geography. . It can be best studied in 

 March, April, or May. 



THE BREAKING OF ROCKS TO MAKE SOIL. 



Evidences. Rocks which are splitting or crumbling to 

 pieces are usually not difficult to find at this season, in the 

 fields or in old stone walls or foundations. Bring into 

 schoolroom, and show that the rock is not everlasting. 



After the children are thus shown what to look for, an 

 out-door lesson may reveal many examples of " rotting " 

 rock. Visit, if possible, a rocky cliff or a bluff, or a street 

 cutting, or an old stone wall. Note the cracks and holes 

 through which water can enter. Often roots can be seen 

 penetrating the rocks. Bring back to school the best, that 

 is, the most " rotten/ 7 specimens. 



Causes. Review, by an experiment if possible, what 

 was learned about the expansion of water when it freezes. 

 Show how water soaks into rocks such as slate, and even 

 into those which seem solid, like the stone window ledges. 

 When this water freezes what may it do? Jack Frost is 

 the greatest agent in breaking up rocks, and in making 

 the soil which the plants must have. Shall we complain if 

 he cracks a few pitchers in which we have carelessly left 

 water ? 



Some of the specimens may ^how how the frost is helped 

 by the growth of the roots, which push into the cracks. 



Show children the limestone incrustation from the tea- 

 kettle which must have been dissolved in the water, and was 

 deposited when the water evaporated. So water dissolves 



