CHAPTER XXXIX 



THE WORK OF THE ATMOSPHERE 



Dust. Wind raises small dust particles aloft and carries 

 them away and sweeps coarse sand particles into drifts on 

 pavements and fields. The dust that settles on the deck of a 

 ship in mid-ocean or on the newly fallen snow of the mountain 

 is blown there by the wind. Shelves and tables in our homes 

 need daily cleaning to keep them free from dust. Deserted 

 houses are sometimes half hidden by the dust which falls on 

 them ; the ancient and deserted city of Nineveh is supposed 

 to have been buried by dust. If the wind is gentle, we are not 



conscious of the dust it 

 carries ; if it is strong, clouds 

 of dust overtake us and make 

 us conscious of its carrying 

 power. 



The cutting power of wind- 

 blown sand. On a windy 

 day, the face is often stung 

 by small soil particles blown 

 against it. The fine sand 

 carried by winds acts as a 

 sharp tool and cuts and wears 

 away glass, rock, and stone 



on which it strikes. Windows and monuments are often badly 

 scratched and marred by the sand hurled against them by wind- 

 Figure 256 shows a sandstone bowlder which has been worn 

 away in part by the constant beating of wind-blown sand ; the 



388 



FIG. 256. A bowlder etched by wind- 

 blown sand. 



