24 



AGRICULTURE ON THE PACIFIC SLOPE 



mountains. At the foot of granite ranges on the Pa- 

 cific Slope, great sloping masses and beds of granite 

 sand ("talus") may be seen (figure 13). These, when 

 freshly formed and coarse, are barren for a number of 

 years; while lower down, the land made from just such 

 materials ground finer is very fruitful, as near Arcadia 



and on the Santa 

 Anita rar^ch in Los 

 Angeles County, 

 California. 



In the granite 

 mountains of the 

 Atlantic States, 

 where much rain 

 falls in summer, we 

 sometimes find the 

 rock softened 



FIG. 13. Sloping masses of rock at the base 

 of cliffs. These slowly change into soil. 



(rotted) for many feet under the soil, so that the 

 s enter it freely to a depth of several feet. This 

 is true also of the western (rainy) portions of Oregon 

 *^and Washington, where the dense forest growth and 

 \*ty\ heavy cover of moss prevent the soil from washing 

 away, while the rapid decay of vegetable matter favors 

 I rock decay to the utmost. 



Humus. We thus see that the decay of plant ma- 

 terial, which in the end forms black humus or vegetable 

 mold, is necessary in order to make good soil. The 

 value of humus arises from its power to take up and 



