STATE HORTICULTURAL SOCIETY. 129 



been verified by cultivation, and the soil proved to be both fertile and 

 durable. We are all familiar with the fact that the drift was not distrib- 

 uted equally over the State. In the northwestern part, the scarcity of 

 boulders and pebbles led to the belief, a few years ago, that it was a 

 " driftless region." Subsequent investigation has, however, established 

 the fact that this was an error, and that the drift did sweep over this as 

 well as other parts of the State. In by far the largest portion of the region 

 in (juestion, the soil rests directly upon the subjacent rocks, magnesian 

 limestones and shales. In this Champaign county. Prof. Worthen says : 

 " The soil in Champaign county is underlaid by irregular alternating beds 

 of clay, gravel, and cjuicksand of the drift formation, to the depth of 

 from 150 to probably 300 feet. Owing to the various material eroded 

 and transported by the drift in its southern course, and its unequal depo- 

 sition, a great variety of soil was deposited." My friend, Col. H. C. Free- 

 man, in an article on '' Soils in Illinois," says : "In portions of Illinois, 

 spots of whitish clay, iare of vegetation, are found. There is another 

 whitish clay, of similar appearance, that forms a considerable extent of 

 surface in the region of the Big Muddy. But this is a stratum of much 

 more recent origin, and often under culture," etc. 



We think the Colonel is in error in relation to this last deposit being 

 of more " recent origin,'' and think that the difference in their fertility will 

 be found to be in a difference in composition of the clays. There is no 

 word so indefinite as that of CLAY, when used by writers on the drift or 

 agriculture. 



It may mean : 



First — Pipe or fire clay, a substance composed of fifty-six to sixty- 

 two per cent, of silica, thirty-six to forty of alumina, and three to four 

 of oxide of iron, chemically combined, and cannot be separated mechanic- 

 ally or by decantation ; or, 



Second — Strongest clay soil, consisting of pipe clay, and fifteen to 

 twenty per cent, of silicious sand, which can be separated from it mechan- 

 ically ; or, 



Third — Clay loam, containing pipe clay, and from fifteen to forty 

 per cent, of fine sand, which can be separated from it mechanically. 



The English writers, in order to distinguish the various clays, have 

 given them local names. Johnson says of 



Pipe Clay — Of various colors, some nearly pure white, and used for 

 making ])ipes ; soil various, alternating with beds of sand ; it produces 

 soils of most unlike (juality, often within a very short distance. 



London Clay — Stiff, almost impervious; brown, blue, and blackish in 

 color, forming a strong, heavy, wet, tenacious soil, sticking to the plow- 

 like pitch. 



Gault Clay — Forms a thin, cold soil, which, when wet, becomes as 

 sticky as glue ; is very expensive to cultivate. 



Weald Clay — Contains much fine sand ; it is pale colored ; the soil, 

 when wet, forms a paste whicli dries and hardens like a brick, so the roots 

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