SOILS. 



549 



value, the mineral elements visible in it not being so 

 readily observable in the finely comminuted soil. 

 Soils of this character are not abundant in NewiEng- 

 land and the regions north of the Ohio, and east of 

 the Missouri, nor in the river valleys of the country. 

 Here they occur only in small patches, as where the 

 friable outcropping red sandstone of the Connecticut 

 valley has crumbled into soil, or where trap bluffs 

 have made soils at their bases. In the more southern 

 and western regions, away from the river valleys, 

 sedentary soils are the rule. 



Transported soils are those in which the material 

 has been removed to a distance from its place of 

 origin by moving agencies, principally ice and 

 water, and deposited elsewhere as sediment. Of 

 these those known as drift or diluvial soils are char- 

 acterized by the rounded edges and surfaces of their 

 larger fragments, and by their lack of stratification. 

 They embrace soils proper and collections of stones, 

 varying in size from grains to great rock boulders, 

 which are scattered indiscriminately through and 

 over the soil. These soils are supposed to be the 

 product of ice action, the work of the great glacial 

 movement which, there is satisfactory reason to be- 

 lieve, took place during the glacial age of geology, 

 affecting the whole country from the Arctic zone to 

 about the latitude of 40, its effects on the soil ex- 

 tending to southern New England, to nearly the 

 southern boundary of Pennsylvania, and to the Ohio 

 River, and extending from the Atlantic to the States 

 west of the Mississippi. The whole of this region is 

 more or less covered with the rock debris moved by 

 the glacier, the material being as a rule transported 

 20 to 40 miles from its place of origin, and in some 

 cases from 60 to 100 miles. Drift soils are often of 

 the most diversified character, including rock ma- 

 terials of great variety, which have been mingled 

 and carried in the ice flow. Of those only the hard 

 granite and silicions rocks occur in large fragments, 

 the softer ones being ground to powder, the fine soil 

 and stones of varied size being of ten indiscriminately 

 commingled. Drift surfaces are usually irregular 

 and hilly, the hills being conical heaps or long 

 ridges of mixed sand, gravel, and boulders, often of 

 great depth. South of the boulder line is a region, 

 occasionally of considerable width, of much finer 

 material, and partly stratified. This is supposed to 

 have been the mud and sand carried by the waters 

 of the melting glacier, and deposited by the streams 

 over a broad area farther south. The sands of 

 southern New Jersey and Long Island may have 

 been due to this process, as well as the fertile soil 

 of southern Pennsylvania. Drift soils greatly vary 

 in productiveness, in consonance with their variety 

 of materials. The soils of New England, for in- 

 stance, are lacking in fertility, while those of Penn- 

 sylvania and Ohio are of unsurpassed excellence. 



Another form of the transported soil is that known 

 as alluvial. This consists of the worn materials 

 transported by running waters, and deposited along 

 the course of overflowing rivers. These are always 

 more or less stratified, the coarser materials on the 

 bottom, the finer on top. The coarser are also de- 

 posited most abundantly along the upper reaches of 

 the rivers, the finer farther down, impalpable mud 

 being carried much farther than sand or gravel. 

 Such soils occur in the valleys of streams, and in 

 silted-up beds of old rivers, lakes, and gulfs. In the 

 United States, much the most extensive deposit of 

 alluvial soil is that laid down in the bottom lands of 

 the Mississippi River and its western tributaries, the 

 Ohio cutting too narrow a channel to leave much 

 space for such deposits. The bottom lauds of the 

 Mississippi, covered everywhere with finely com- 

 minuted materials abraded by the river and its tribu- 

 taries from the head-water and bordering regions of 

 the streams, and deposited along the more level 



lower reaches of the river, average 40 miles in 

 breadth, and extend for a distance of 500 miles, the 

 stream winding through them with a length of 1,100 

 miles. Their total areu is about 32,000 square miles, 

 much of it of great depth of soil and almost inex- 

 haustible fertility, though comparatively little of it 

 is yet cultivated. 



Soils in which drift and alluvial are mingled with 

 sedentary materials, have been named colluvial 

 soils. They are distinguished by the presence in 

 transported material of sharp-angled fragments of 

 original rock, that have evidently not been carried 

 far. Such soils are of comparatively small extent. 

 Of other distinctive American soils, maybe mentioned 

 those of the prairie States, which are distinguished 

 by the absence of trees and the great depth of their 

 fertile material. They probably belong to the allu- 

 vial class, being produced by the gradual silting up 

 of great, shallow lakes, which formerly may have 

 occupied this whole region. Their productive powers 

 seem to be increased by the processes of cultivation, 

 and seem almost inexhaustible, many years of cereal 

 production without manuring showing little percep- 

 tible diminution in abundance of crops. In the 

 western borders of the prairie region fertility is 

 diminished by the lack of rain. In respect to its 

 rainfall, the United States may be divided into two 

 nearly equal portions by the meridian of 100. The 

 region east of that meridian has a sufficient and 

 pretty regular distribution of rain ; that westward is 

 irregularly and insufficiently supplied, except a nar- 

 row belt on the Pacific coast. Part of the latter is 

 abundantly supplied ; part of it irregularly but in 

 fair sufficiency ; while iu pai't of it the rain is insuf- 

 ficient for agriculture. Much of this region is, and 

 must remain, essentially pastoral in its uses, though 

 through a considerable portion of it irrigation has 

 taken the place of rainfall, and abundant crops are 

 raised from the highly fertile soil. The specially 

 arid region of tho United States is that known as the 

 Great Basin, a vast district with an area of about 

 225,000 square miles, which constitutes an elevated 

 plateau between the Rocky and the Coast mountain 

 ranges, which, from its rainless character and the 

 impossibility of irrigation, must remain permanently 

 useless in an agricultural sense. (See GREAT BASIN.) 



We may conclude with a brief consideration of the 

 several varieties of soils, and their distinctions of 

 physical and agricultural character. Plants derive 

 their food from the fine, and particularly from the 

 finest particles of the soil, of which a very small per- 

 centage is available for plant-food at any one time. 

 But the larger particles are equally useful, from their 

 aid in keeping the soil open and permeable, while 

 through their gradual disintegration they furnish 

 new plant-food. Gravelly soils are so named from 

 their abundance of small stones or gravel. Such 

 soils may be poor or rich, in conformity with the 

 character of their fine material, and also the com- 

 position of their gravels. If there be many pebbles 

 of felspar, tho soil will probably be well supplied 

 with alkali ; if of limestone, with lime ; if of quartz, 

 the soil will be poor. Sandy soils are those which 

 contain 90 per cent, or more of sand, or small grains 

 of rock of any kind. If the sand be composed of 

 nearly pure quartz grains, the soil will be barren, but 

 generally other minerals, such as felspar and mica, 

 are present, and iron compounds exist where the 

 sand is red or yellow. These minerals, by their de- 

 composition, often give considerable fertility. The 

 green-sand of New Jersey is used as a fertilizing 

 material, it containing much organic substance. Tbe 

 term sandy soil is, therefore, very indefinite as re- 

 gards fertility. Coarse sandy soils are usually un- 

 profitable, but fiiie sand is often agriculturally valu- 

 able. 



Clayey soils, physically considered, stand at the 



