Soil-Carriers 49 



yet the fields seem to get it — and that, too, without the 

 drawback of being suffocated every few years. Where 

 does it come from ? 



The wind blows chiefly from the west and south- 

 west, across the mountain-chain of the Ddmes. The 

 air on the western side of the mountains is bright and 

 clear, but that on the Limagne side is generally slightly 

 hazy, and the haze seems to consist of fine dust. And 

 when we inquire about the mountains, we find that 

 they are extinct volcanoes, and are widely strewn with 

 volcanic ashes, the relics of ancient eraptions, rich in 

 the minerals which make the most fertile soils, and 

 just in the condition in which plants can most readily 

 make use of them. 



It seems, therefore, that the inexhaustible fertility of 

 the Limagne is in great part due to these constant 

 supplies, which are carried across the country by the 

 sometimes severe wind, and naturally fall when it sub- 

 sides, besides being brought down by rain and snow. 



The English proverb declares that * a peck of March 

 dust is worth a king's ransom,' and there can be no 

 doubt that the clouds of dust blown upon the fields 

 from the high-roads are most valuable. So, too, in 

 spite of all their drawbacks, are the dust-storms which 

 occur from time to time in certain regions — as, for in- 

 stance, in Western Iowa, where the air is filled for 

 days together with dust of the finest description. 



