130 ELEMENTARY GEOLOGY 
When a violent volcanic eruption occurs, and great: 
quantities of dust-like ash are thrown into the air, the 
wind bears it far and wide, strewing it over the land 
and ocean. Ash thus transported, has fallen at dis- 
tances of scores and even hundreds of miles from the 
place of eruption. 
Another notable action of the wind is that of blow- 
ing the finer rock and soil particles hither and thither, 
distributing them over the land. This action of the 
wind is particularly noticeable, (1) on the sea or lake 
shore; (2) in dry countries. 
In most parts of the moist regions of the earth the 
ground is usually damp, and is protected from the 
wind by a covering of vegetation. Since this is true 
of the climate in which men chiefly dwell, we are not 
accustomed to consider the wind as a prominent agent 
of erosion. ? 
On the tops of mountains, where the wind is fierce, 
and where, because of the cold, vegetation is either 
very scanty or entirely absent (Fig. 55), the wind is of 
service in removing the finer particles of. rock decay. 
The same is true in arid and desert lands, where little. 
or no vegetation covers the soil to protect it from the 
blasts (Figs. 59 and 66). Here, on every windy day, the 
surface soil is in motion, and at times clouds of sand. 
rise in the air, shutting from view even the neigh- 
boring hills. These blinding “sandstorms” are well 
