(luiuididii Foicsliij Journal, March, I'.lIT 



1011 



TOBOGCAMNG IN SAND 

 A scene in Prince Edward County, Ontario, where the stripping of tree life created a costly problem 

 in the ci eating of sand dunes. 



capable of holding several times its own weight of water. As the rain falls 

 it is absorbed by this sponge, then passed on to the reservoir of mineral soil 

 beneath, and finally fed out gradually to the springs and streams. Then, 

 too, surface run-off is checked by the mechanical obstruction offered;. by 

 stumps, fallen twigs, branches, and even whole trees; and percolation of the 

 water into the soil is made easier by the network of small roots and the chan- 

 nels left by the decay of large roots. ' Even when the rain is so heavy that 

 the soil is unable to absorb all of the water at once, the excess flows off with 

 no erosion. Streams coming from virgin forests are seldom muddy and are 

 subject to comparatively small variations in flow. 



When Rain Falls on Exposed Soil 



The effect of heavy rains on the exposed soil of cleared fields is very differ- 

 ent. Ther.e the rain beats upon the bare ground like millions of little ham- 

 mers. The soil is compacted, its absorbing capacity is reduced, and first 

 the finer and then the coarser, infertile particles are washed away. The 

 water quickly gathers into little rivulets, then into streams, and finally into 

 roaring torrents, all carrying with them ever-increasing quantities of soil 

 and often stones and bowlders. Myriads of tiny channels appear as if by 

 magic. These run together into small gulhes, and the small gullies grow into 

 larger ones. The whole area is cut up by erosion and the eroded materials 

 carried away to cause trouble at lower elevations. 



The Causes of Erosion 



Injudicious clearing for cultivation of land on which a forest cover should 

 always have been maintained has been one of the main causes of unnecessary 

 erosion. Thousands of acres on slopes too steep for successful farming have 

 been ruined in this way. Such land has been cheap and the settler frequently 

 has been only too ready to cultivate it for a few years until it was worn out 

 and then complacently move on to repeat the process elsewhere. Improper 

 methods of agriculture have often hastened the devastation. Unfortunately, 

 this has not been confined to the area itself. Once started, erosion has pro- 

 gressed in both directions, washing out and burying fertile lands below and 

 eating back into forested lands above. 



Complete clearing of lands that should have been only partially cleared 

 has had the same result. Not infrequently it happens that part of an area 



