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BUREAU OF CHEMISTRY AND SOILS, 1926
                               SOILS
  The upland soils of Manitowoc County are classed with the gray-
brown soils of the forested part of the humid region south of
the Great Lakes. They developed under conditions of climate and
surface features which favored the growth of forests. Light-colored
surface soils developed in the forests and dark-colored surface soils
on prairie areas in this same general region. There are areas of
dark-colored soils in this county, but the dark color was caused
primarily by poor drainage rather than by a grass vegetation. With
the exception of small areas of open marsh, the whole county was
forested before the region was settled by white men.
  The most striking feature of the soils of the county is that the
predominant soils are heavy or fine textured. The county lies within
what is usually known as the red-clay section of Wisconsin.
  The soils of the county naturally fall into two major classes, the
well-drained, normally developed or mature soils, and the immature
soils.
  The first group includes soils of the well-drained uplands derived
from glacial till and soils of the better-drained areas on old glacial-
lake and alluvial terraces.
  In this region the normally developed or mature soils are weath-
ered to a depth of 3 or more feet, depending on the surface relief
and composition of the parent materials.
  The most typical mature soils in the county developed from glacial-
till parent material. These soils are characterized by a consistent
profile which shows a grayish-brown friable surface soil, a rather
heavy light-brown or reddish gravelly clay subsoil, and a light-
brown or reddish-brown glacial-till substratum, which is the parent
material.
  The surface soil includes the friable comparatively light-textured
upper layers from which much of the clay material including the
inorganic colloids has been removed. The subsoil is the rather heavy
layer where much clay material, including colloids, has been depos-
ited by percolating water in the course of weathering. This horizon
has a coarsely granular structure and is neutral or slightly acid in
reaction. The third main layer or horizon is the parent material,
the unweathered or only slightly weathered material from which
the soil has developed. This horizon has no regular structure. It
contains sufficient lime to effervesce freely with hydrochloric acid.
  The parent soil material consists largely of two very different
kinds of glacial till, the older brown till and the more recently
deposited so-called red till which overlies the brown till. Extensive
areas of soil materials on glacial terraces and flood plains are from
the same original sources but have been reworked and redeposited
by water.
   The brown till is usually considered to have been formed by the
grinding up of the underlying dolomite bedrock, with some admix-
ture from the crystalline rocks to the north. The red till is usually
considered to be partly composed of rock debris and partly of glacial
lake sediments carried southward from the Lake Superior region.'
  8 ALDN, W. C. QUATERNARY GEOLOGY OF SOUTHEASTERN WISCONSIN, WITH A CHAPTER
ON THE OLDER ROCK FORMATIONS. U. S. Geol. Survey Prof. Paper 106, 356 p.,
illus. 1918.
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