AGRICULTURE 



bottom of the glass will be a sediment of mud. This is soil which 

 the rain washed down into the brook. The amount in one 



glass of water is small, but 

 think how much the brook and 

 all the other streams transport. 

 Where a rolling field is un- 

 drained and badly tilled, every 

 rain steals some of its fertil- 

 ity; later you will learn how 

 a, farmer can protect his land 



On me left is a glass of muddy water; on against SUCh thefts. 



the right is the same a few hours later, 

 showing sediment. 



Alluvial Soils. Streams bear 

 down to the ocean a vast amount 

 of soil, but far less than they get from the hillsides. Like greedy 

 children, they take more than they want and have to leave part. 

 They drop it in shallows and leave it along the banks. This 

 material, deposited by water, forms al lu'vi al soils. They are 

 usually fertile loams, rich in organic matter. 



Egypt, ' the gift of the Nile/ is formed of soil brought from distant 

 mountains by heavy rainfalls and floods. So Louisiana is the 

 gift of the Mississippi. The sediment which forms its fertile soil 

 has been brought hundreds of miles by the river. Each year the 

 Mississippi carries to the ocean enough soil to cover two hundred 

 and sixty-eight square miles with a layer one foot deep. 



Drijt Soils. Most of the soil of America in the great area north 

 of the thirty-ninth parallel is a transported soil. It was formed, 

 not by streams of water, but by gla/ciers, or streams of ice. 



-The Glacial Period. Thousands of years ago, the climate in the 

 region north of the equator became very cold. There came a long, 

 long winter which destroyed plant and animal life. Snow fell until it 

 was hundreds and thousands of feet deep. This formed a glacier, 



