22 



MISC. PUBLICATION 3 9 5, U. S. DEPT. OF AGRICULTURE 



Upon leaving the open and entering the cool shade of the woods they will note 

 the forest floor — the undergrowth of young trees and shrubs, the ferns and moss, 

 and the litter of fallen leaves. With a jackknife, or a trowel, they can dig beneath 

 this cover into the mold of many years' fallen leaves. The soil will be spongy and 

 moist. What happens when rain falls or snow melts? Under the forest canopy 

 it sinks into the spongy earth (fig. 16). 



What becomes of the rain and snow that the forest has soaked up like a sponge? 

 Find a spring. This is where the stored water is seeping out to feed the streams. 

 The rainfall that has been held back in the hidden reservoir of the forest is here 

 transformed into a steady supply of water for the pasture, the farm, the mill, 

 and the city. 





F-34411 



Figure 16. — The forest floor: Dense growth of seedling and sapling trees covering and protecting the 

 soil; leaves and twig litter on the ground beneath the trees; spongy layer of decomposed vegetable 

 matter or humus, and the lower layer of soil interlaced with tree roots and rootlets; and the clay 

 subsoil. 



Return to the open and dig into the soil on the unwooded slope. It will be 

 found dry and hard. What happens when the rain falls or the snow melts on the 

 open hillside? It is not held back and absorbed but rushes down the slope. In 

 a heavy rain the streams rise rapidly. Perhaps the group will find a place where 

 a bridge has been carried away in a freshet. Someone may tell of the destruction 

 of a log bridge on the farm. What happens when the winter snow melts upon 

 the unprotected mountain slopes and the spring rains swell the rivers? (Figs. 17 

 and 18.) 



On the open hillside, places will be found where the soil, which has no roots to 

 bind it, has been washed away by the rain, and on some steep slope there will be 

 deep gullies dug into the ground. Where does the soil go that is washed down the 

 slope? Into the stream. Perhaps the stream carries the silt into the water supply 

 of a city. If there is a river near, a sand bar may be found that has resulted from 



