Effects of wind on plants.—Another effect of wind work is seen in the uprooting of trees ([Fig. 25]). The uprooting disturbs the surface in such a way as to make loose earth more readily accessible to wind and water. The uprooting of trees on steep slopes often causes the descent of considerable quantities of loose rock and soil. Again, organisms of various sorts (certain types of seeds, germs, etc.), as well as dust and sand, are extensively transported by the wind. While this is important biologically its geological effects are remote.
Fig. 23.—Figure showing details of wind-carving on rock surface (rhyolite). Mono Valley, California.
Fig. 24.—Wind-worn stones (Dreikanter).
Fig. 25.—Shows the disturbance of surface earth and rocks by upturning of trees. (Darton, U. S. Geol. Surv.)
Indirect effects of the wind.—Other dynamic processes are called into being or stimulated by the atmosphere. Winds generate both waves and currents, and both are effective agents in geological work. The results of their activities are discussed elsewhere.
II. The Chemical Work of the Atmosphere.
The chemical work of the atmosphere (including solution and precipitation from solution) is principally accomplished in connection with water, a dry atmosphere having relatively little direct chemical effect on rock or soils.