176 NATURAL HISTORY OF THE FARM 
that does not extensively destroy the roots nor remove 
ground-cover. She fines the surface with the heav- 
ing of winter frosts. She 
stirs the deeper parts by 
the borings of earthworms, 
by the excavating of burrows 
for the homes of mammals, 
and by the overturn of the 
roots of windfall trees. It 
is here a little and there a 
Fic. 68. Diagram of a section of a partly little, but in the long run it 
wooded hill. J, original contour of the . 
hill slope; m, contour assumed after 1S thoroughly done. 
tilling of the fields; 2, in-wash of soil 
above; and o, out-wash of soil below. We can see the contrast be- 
tween nature’s soil manage- 
ment and our own on almost any slope where both fields and 
woodsoccur. Wherever their boundariesrun horizontally, such 
contours as are indicated in figure 68 result from the rapid 
slipping away of the topsoil of our tilled fields. A ridge is 
formed along the edge of the wood when the bare field lies 
aboveit: the soil washed from the field is held by the ground 
cover herbage at the edge of the woodland. When the field 
lies below, a hollow is formed at the edge of the wood where 
the tree roots cease to hold the soil together. To be sure, 
gravity is always operating, and the soil of the woods is slowly 
shifting to lower levels; but it is only inthe fields, where the 
ground-cover is removed and the root-hold periodically 
broken, that the process goes on sorapidly that the soil seems 
to melt and vanish before our eyes; it is only here and with 
very bad management, that the organic products of one 
season are all taken from it before the next season comes 
around. 
Let us go into the woods and look at the soil there. The 
first thing we notice is that there is little soil to be seen—only 
a few paths kept bare by passing feet. Here and there are 
Freep 
