64 SOILS 



and partly blown there from elsewhere. They 

 are exceedingly sticky when wet and bake very 

 hard when dry, so that they are used for building 

 purposes. This makes them very hard to work; 

 in short, they are aggravated clay soils. When 

 they are wet enough they are remarkably pro- 

 ductive, as they are unusually rich in plant food. 

 Some adobe soils are very deep those in some of 

 the valleys of the arid regions being over 2,000 

 feet deep. 



Adobe soils are usually light buff or gray, ex- 

 cept when they contain a considerable quantity of 

 humus, which makes them darker. They are very 

 fine grained; no grit is felt when adobe is rubbed 

 between the fingers. The depth, fineness and 

 virginal fertility of adobe soils, since they have lost 

 very little from leaching, makes them wonderfully 

 productive. These soils are quite similar to the 

 loess soils of the Central West. 



SALT MARSH SOILS 



All along the Atlantic Coast, and especially in 

 New England, are thousands of acres of marsh 

 land that some day will be used for farm crops. 

 They are made largely from soil that has been 

 worn by the sea from the rocks on the coast. Each 

 wave that curls its crest over the "stern and rock- 

 bound coast" wears it away to some extent, as is 

 witnessed by the honeycombed rocks at Marble- 

 head and elsewhere. The headlands that project 

 into the sea are worn down and strewn upon the 

 beach as sand. Each wave that comes tumbling 

 in grinds these rock particles a little finer we can 

 hear them rustle and grind against each other in 

 the undertow. After a while the coarse sand of the 



