194 GEOLOGY OP EASTERN WISCONSIN. 



ly cubical blocks, so that when dug np it is neither pulverulent nor 

 aggregated in rounded clods, as is the case with arenaceous and loamy 

 soils, but is simply a heap of little blocks. From this portion the 

 carbonates have been pretty thoroughly removed. Hydrochloric acid 

 seldom produces effervescence, never any vigorous action. The Assur- 

 ing is to be regarded as the cause rather than as the result of this re- 

 moval of the soluble carbonates. The color of this portion is also 

 somewhat duller and more inclined to a mottled and brownish hue 

 than the lower unmodified portion, which is usually a pinkish or pur- 

 plish red. This lower portion is the true subsoil, and is the part 

 previously described. The immediate s^lrface has an ash color. 



This soil needs thorough working, which is not so easily accom- 

 plished as with the loamy arenaceous soils, but it yields excellent re- 

 turns. It is an exceedingly strong, durable, fertile soil. Its strength 

 lies in its native constitution and not in a superficial layer of vegeta- 

 ble mold, soon to be exhausted. Cultivation improves rather than 

 exhausts it, and it will still continue to yield bountiful harvests when 

 many other soils will need the constant stimulus of fertilizers. The 

 stirring, the washing out of the finer materials, and the exposure to 

 the air incident to cultivation, give it a lighter and warmer character, 

 so that after a few years cultivation, crops may profitably be intro- 

 duced that at first were unsuccessful. 



The map shows it to occupy a belt along Lake Michigan, from Mil- 

 waukee to Sturgeon Bay, widening to the northward until it passes 

 the summit between the lake and the great valley, and occupies the 

 basin of the Fox river and Lake Winnebago. 



Class V. Th& Limestone Loam. This is not a very sharply de- 

 fined class. It appears to have its origin in the decomposition of the 

 magnesian limestone upon which it rests. It thus differs from either 

 of the marly clays, to which it is most nearly allied, in not being a 

 drift soil. It is usually yellowisli or reddish in color, rather plastic 

 and adhesive, moderately comminuted, of only medium porosity, and 

 in chemical nature it is chiefly silicious and aluminous, or in the lan- 

 guage of its origin, the insoluble residue of the limestone. The car- 

 bonates of lime and magnesia, though, forming the chief constituents 

 of the original rock, are present in the soil in very limited quantities. 

 This makes the use of the name here given objectionable, if it is 

 thought to indicate the composition of the soil. It was selected for 

 want of a better one to indicate its origin. 



The depth of the soil, except in the valleys, is not considerable, and 

 the rock itself is really to be regarded as the permanent subsoil. It is 

 reached even by the roots of cereals over much of the area occupied 



