188 GEOLOGY OF EASTERN WISCONSIN. 



CHAPTER IV. 

 SOILS. 



There are few subjects upon which it is more difficult to make an 

 accurate, aud at the same time an intelligible report, than upon soils. 

 This difficulty arises partly from the nature of the subject, and partly 

 from the vagueness of the terms used in speaking of soils. Aside 

 from the vagueness, these terms have a different signification as used 

 by different persons, which adds to the difficulty. We speak of " light 

 soils " and " heavy soils," and perhaps, without thinking, we suppose 

 that these terms refer to actual weight, or, in the terms of science, 

 to specific gravity. But such is not usually the fact. Thus, we say, 

 "a heavy clay soil" and "a light sandy soil," but in fact the weight 

 of the clay soil is only about three-quarters of that of the sandy soil, 

 measure for measure. These terms, as commonly used, really refer 

 to adhesiveness, degree of comminution, or power of holding water, 

 or, more properly, perhaps, to the way in which the soil "works." 

 Again, the term " sandy soils " is supposed, even by persons some- 

 what versed in the sciences, to mean those that are made up of grains 

 of quartz; or, in other words, are silicious, and hence are more or less 

 barren. But this is not always true. Some sandy soils are composed 

 of grains of limestone, and are very fertile, an instance of which will 

 be described presently. So, a clay soil is supposed by many some- 

 what intelligent in chemistry, to be composed of aluminous material, 

 but this is far from always being the case, as the term is commonly 

 used. 



This obscurity will, however, in a measure, disappear as we proceed 

 to consider the origin of the soils of Eastern Wisconsin, which appro- 

 priately claims our attention here. 



The organic constituents of the soil have manifestly been derived 

 from the plants that the soil has itself produced, and are only the re- 

 sult of accumulated self -enrichment. Local exceptions to this are to 

 be found in those cases where soils have received organic material 

 washed from adjacent areas. This vegetable matter takes various 

 forms, but all may be spoken of under the comprehensive term, 

 liumus. In marshy locations, the moisture prevents the decay of 



