FRUIT-GROWERS’ REPORT. 
381 
north of Racine, and lias its greatest breadth east and west 
through the middle of Lake Winnebago. 
The Potsdam sandstone is developed north of the lime region T 
with the exception of a small tract lying east of Lakes Pepin and 
St. Croix, where the limestone prevails. There is also a small 
tract of sand found in Dane and Green counties, on the Sugar 
river, and another at the head of the Crawfish, in Columbia,, 
and the bed of the Wisconsin; but these are the intermediate 
sands, and occupy so small spaces as scarcely to deserve notice 
in the general estimate. 
The lime region must be again divided into the region of the ' 
drift, where are found gravel and sand beds, sometimes reaching 
to great depths, and dt others piled into small cobbled hillocks 
and ridges; and the region where the rocks have not been moved 
or covered with water since the boulder period, lands which were 
out of water before the coal fields of Illinois were formed, and 
have not since been below it. These last regions are embraced 
in the counties of Grant, La Fayette, Iowa, and the wnstern 
portions of Green and Dane, and north of them. In these por¬ 
tions the surface rocks sliow T no worn or washed gravel beds, no 
worn rocks on the high lands, no boulders can be found, nor 
have the'surface rocks been disturbed for a series of times. 
I desire to call your attention to one peculiarity in the soil of 
Wisconsin, which I have not seen noticed by the Geologists of 
the State. For we are dealing with the soil, and not with the 
geology in the properly understood acceptation of that term. I 
allude to a peculiar formation on the surface of the wdiole lime¬ 
stone country, except some of the liill-sides and bluffs, where 
the rock and gravel are exposed to view. If the surface soil is 
removed to the depth of from six to twelve inches, there will be 
found a substance from two to ten feet in thickness much resem¬ 
bling clay, and commonly mistaken for that mineral, more or 
less red according to the quantity of iron entering into its 
composition; a chemical analysis of which will, however, disclose 
the fact that it contains but a very small proportion of alumina, 
or clay, and that it is, in fact, nearly all silica, or sand, so finely 
reduced that it will scarcely polish the cast steel plow of the 
