EARTHS AND SOILS. 49 



sandy, except where the formation is aided by fresh-wa- 

 ter streams, in which case clay is found extensively mixed 

 with sand, as also marine shells and vegetable matters. 

 Of the latter class of alluvial soils, those created by riv- 

 ers, the earthy elements are more generally blended with 

 a greater admixture of organic matters. Where the de- 

 posit has been made by a rapid current, gravel or small 

 stones will predominate, and the soil will be comparative- 

 ly poor. As the force of the stream abates, sand will 

 next subside, while the finer earthy and enriching matters 

 will be found deposited upon the borders of still waters. 

 Where alluvial grounds are subject to frequent, or to 

 annual inundation, and the character of the soil will per- 

 mit, they should be appropriated to permanent grass. If 

 tilled, the soil is liable to be worn away or injured, and 

 the crops destroyed, by freshets ; while, if in grass, the 

 deposits made by the waters will tend to keep up fertility. 

 If not subject to floods, they may be cropped, as uplands 

 of the same character are cropped. 



7. Loams. — " Where a soil is moderately cohesive, 

 less tenacious than clay, and more so than sand, it is 

 known by the name of loam. From its frequency, there 

 is reason to suppose, that, in some cases, it might be 

 called unoriginal soil. At the same time, a constant 

 course of tillage for ages, the application of fertilizing 

 manures, where necessary, (as clay with sand, or sand 

 where clay predominates) will necessarily convert a soil 

 thus treated into a loam. 



'' Loams are the most desirable of all soils to occupy. 

 They are friable ; can in general be cuhivated at almost 

 any season of the year ; are ploughed with great facility and 

 less strength than clay ; bear better the vicissitudes of the 

 seasons ; and seldom require any change in the rotation 

 adopted. Above all, they are peculiarly well adapted 

 for the convertible husbandry ; for they can be altered, 

 not only without injury, but generally with benefit, from 

 grass to tillage, and from tillage to grass. They should 

 not, however, be kept in tillage too long, nor while they 

 are in cultivation should two white crops be taken in suc- 

 cession. 



5 XV. 



