84 MAN ON THE LANDSCAPE 



year. Except in the case of drizzles or snow, this enormous weight 

 drops from the skies with a velocity which gives it tremendous strik- 

 ing power. Knowing these facts it is perfectly clear that rain of even 

 average intensity cannot fall without marked effect. An intense rain- 

 storm may in one day skin off a half inch of soil from bare land 

 soil which was from 100 to 500 years in the making. The reaction 

 may take at least two forms : 



(1) Loam soil is granular in structure. This permits the circula- 

 tion of air, the infiltration of water, and promotes moisture adsorp- 

 tion as a thin film on the soil particle surfaces. These three factors 

 are highly beneficial to plants. The impact of a raindrop breaks up 

 the soil crumbs or aggregates on the surface. The finer materials 

 then clog the soil pores, reducing aeration and infiltration. The 

 total reaction is significant injury to the productive capacity of the 

 land. (Figs. 39, 40, 41.) 



(2) The second direct result of drop impact on bare soil occurs 

 on sloping land only. (There is very little land which does not slope.) 

 The raindrop fragments the granules and also dislodges already 

 existing fine particles. These particles adhere to the water of the 

 shattered raindrop, or go into solution with it, and are carried by its 

 splash in all directions. Gravity operates, causing more of the ma- 

 terials (water and soil) to fall downhill than uphill. Thus, without 

 even taking into account the erosion due to running surface water, it 

 is obvious that the soil will be gradually knocked downhill by billions 

 of drop impacts. (Fig. 42.) The farmer eventually will be knocked 

 off the land, economically speaking, and much life directly useful to 

 man on such areas will be diminished toward zero. 



Is this unexpected? Is not the raindrop chained to its reaction? 

 Is the soil not obedient to natural law in reacting as it does? 



Is there an alternative which corresponds to the shooter's end of 

 the autoloading gun, where natural reactions can be turned to man's 

 benefit? There is. Furthermore, natural processes provide it. Vege- 

 tation diffuses the raindrop reaction and prevents destructive effects. 

 It does this most efficiently when the climax vegetation is reached. 

 The raindrop never or seldom strikes bare soil; the resilient canopy 

 and the ground litter prevent it. (Fig. 43.) 



When man disrupts natural organization he must be prepared 

 to take the consequences. Or, he must, through intellect and science, 

 provide cushions against the impacts of natural forces. 



The Tensions of Unbalance. Life succession on its way toward a 

 climax formation might be compared with a flexible, internally active 

 sphere powered by the sun, rolling uphill. As it rolls, the sphere 

 bulges, now here, now there, but always recovers its internal equili 

 brium. Let us imagine that as it rolls, it becomes more highly or- 

 ganized internally. Finally it comes to rest at the top of the hill, but 

 still it teeters occasionally, and bulges with an internal disturbance at 

 times ; but, in the main it is relatively secure in its high position, and 

 its internal troubles are not serious. 



