46 



Conservation of Natural Resources in California. 



and Gulf States at several thousand square miles; and in portions of 

 this region the waste involves a complete removal of a superficial 

 geologic deposit, well adapted to forming a productive soil, from under- 

 lying older formations ill suited to the development of fertile soils and 

 subsoils, in which case the loss is irremediable. 



Other estimates of soil-waste rest on the determination of soil-matter 

 transported by our running waters. The most extensive measurements 

 of this kind were those of Generals Humphreys and Abbott, made on the 

 Mississippi over half a century ago. These showed that the Mississippi 



What happens when the wooded cover is removed from the 

 land. Erosion sets in; and the land turns a bare, unsmiling face 

 toward the sky. Vegetation can get no foothold. The world has 

 lost some of its power to feed its people. 



then carried annually into the Gulf something over four hundred million 

 tons of solid matter, in addition to great quantities of earth-salts, car- 

 ried in solution, and of sand or other coarse material rolled or swept 

 along the bottom. 



At the time of these determinations settlement in the Mississippi 

 Valley was comparatively limited, and, as shown by local observations 

 on different rivers, the effect of extending agriculture has been to 

 increase the soil-matter carried by the Mississippi fully twenty-five per 

 cent; while comparative determinations made on several other streams 

 indicate that the rivers of the country outside of the Mississippi basin 

 carry into the sea about as much soil-matter as the great river itself 

 that is, that the annual soil-wash of the United States aggregates fully 



