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The history of Columbia County, Wisconsin, containing an account of its settlement, growth, development and resources; an extensive and minute sketch of its cities, towns and villages--their improvements, industries, manufactories, churches, schools and societies; its war record, biographical sketches, portraits of prominent men and early settlers; the whole preceded by a history of Wisconsin, statistics of the state, and an abstract of its laws and constitution and of the constitution of the United States
(1880)

Chamberlin, T. C.
Topography and geology,   pp. [110]-120 PDF (5.3 MB)


Page 117


TOPOGRAPHY AND GEOLOGY.
117
unconformably upon it. Where the sandstone abuts against the sides of the
limestone promi-
nences, it is mingled with material derived by wave action from them, which
tells the story of
its formation. But aside from these and other exceptional impurities, the
formation is a very
pure sandstone, and is used for glass manufacture. At most points, the sandstone
has never become
firmly cemented and readily crumbles, so that it is used for mortar, the
simple handling with pick
and shovel being sufficient to reduce it to a sand. Owing to the unevenness
of its bottom, it
varies greatly in thickness, the greatest yet observed being 212 feet, but
the average is less than
Ioo feet. Until recently, no organic remains had ever been found in it, and
the traces now col-
lectedl are very meager indeed, but they are sufficient to show the existence
of marine life, and
demonstrate that it is an oceanic deposit. The rarity of fossils is to be
attributed to the porous
nature of the rock, which is unfavorable to their preservation. This porosity,
however, subserves
a very useful purpose, as it renders this pre-eminently a water-bearing horizon,
and supplies some
of the finest Artesian fountains in the state, and is competent to furnish
many more. It occupies
but a narrow area at the surface, fringing that of the Lower Magnesian limestone
on the south.
                                     TRENTON LIMESTONE.
     A slight change in the oceanic conditions Caused a return to limestone
formation, accompa-
 nied with the deposit of considerable clayey material, which formed shale.
The origin of the
 limestone is made evident by a close examination of it, which shows it to
be full of fragments of
 shells, corals, and other organic remains, or the impressions they have
left. Countless numbers
 of the lower forms of life flourished in the seas, and left their remains
to be comminuted and
 consolidated into limestone. A part of the time, the accumulation of clayey
matter predominated,
 and so layers of shale alternate with the limestone beds, and shaly leaves
and partings occur in
 the limestone layers. Unlike the calcareous strata above and below, a portion
of these are true
 limestone, containing but a very small proportion of magnesia. A sufficient
amount of carbon-
 aceous matter is present in some layers to cause them to burn readily. LThis
formation is quite
 highly metalliferous in certain portions of the lead region, containing
zinc especially, and con-
 siderable lead, with less quantities of other metals. The formation abounds
in fossils, many of
 them well preserved, and, from their great antiquity, they possess uncommon
interest. All the
 animal sub-kingdoms, except vertebrates, are represented. The surface area
of this rock borders
 the St. Peter's sandstone, but, to avoid too great complexity on the map,
it is not distinguished from
 the next formation to which it is closely allied. Its thickness reaches
120 feet.
                                   THE GALENA LIMESTONE.
     With scarcely a change of oceanic conditions, limestone deposit continued,
so that we find
reposing upon the surface of the Trenton limestone, 250 feet, or less, of
a light gray or buff
colored highly magnesian limestone, occurring in heavy beds, and having a
sub-crystalline struc-
ture. In the southern portion of the state, it contains but little shaly
matter, but in the north-
eastern part, it is modified by the addition of argillaceous layers and leaves,
and presents a bluish
or greenish-gray aspect. It receives its name from the sulphide of lead,-galena,
of which it
contains large quantities, in the southwestern part of the state. Zinc ore
is also abundant, and
these minerals give to this and the underlying formation great importance
in that region. Else-
where, although these ores are present in small quantities, they have not
developed economic
importance. This limestone, though changing its nature, as above stated,
occupies a large area in
the southwestern part of the state, and a broad north and south belt in east-central
Wisconsin.
It will be seen that our island is growing apace by concentric additions,
and that, as the several
formations sweep around the central nucleus of Archrean rocks, they swing
off into adjoining
states, whose formation was somewhat more tardy than that of Wisconsin


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