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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 116


HISTORY OF WISCONSIN.
was no crumpling or metamorphism of the strata, and they have remained to
the present day
very much as they were originally deposited, save a slight arching upward
in the central
portion of the state. The beds have been somewhat compacted by the pressure
of superin-
cumbent strata and solidified by the cementing action of calcareous and ferruginous
waters, and
by their own coherence, but the original character of the formation, as a
great sand-bed, has not
been obliterated. It still bears the ripple-marks, cross-lamination, worm-burrows,
and similar
markings that characterize a sandy beach. Its thickness is very irregular,
owing to the uneven-
ness of its Archaean bottom, and may be said to range from rooo-feet downward.
The strata
slope gently away from the Archaean core of the state and underlie all the
later formations, and
may be reached at any point in southern Wisconsin by penetrating to a sufficient
depth, which
can be calculated with an approximate correctness. As it is a water-bearing
formation, and the
source of fine Artesian wells, this is a fact of much importance. The interbedded
layers of lime-
stone and shale, by supplying impervious strata, very much enhance its value
as a source of
fountains.
                               LOWER MAGNESIAN LIMESTONE.
     During the previous period, the accumulation of sandstone gave place
for a time to the
formation of limestone, and afterward the deposit of sandstone was resumed.
At its close, with-
out any very marked disturbance of existing conditions, the formation of
limestone was resumed,
and p-rogressed with little interruption till a thickness ranging from 50
to 250 feet was attained.
This variation is due mainly to irregularities of the upper surface of the
formation, which is
undulating, and in some localities, may appropriately be termed billowy,
the surface rising and
falling ioo feet, in some cases; within a short distance.' This, and the
preceding similar deposit,
have been spoken of as limestones simply, but they are really dolomites,
or magnesian limestones,
since they contain a large proportion of carbonate of magnesia. This rock
also contains a
notable quantity of silica, which occurs disseminated through the mass of
the rock; or, variously,
as nodules or masses of chert; as crystals of quartz, filling or lining drusy
cavities, forming
beautiful miniature grottos; as the nucleus of otilitic concretions, or as
sand. Some argillaceous
matter also enters into its composition, and small quantities of the ores
of iron, lead and copper,
are sometimes found, but they give little promise of value. The evidences
of life are very
scanty., Some sea-weeds, a few mollusks, and an occasional indication of
other forms of life
embrace the known list, except at a few favored localities where a somewhat
ampler fauna is
found. But it is not, therefore, safe to assume the absence of life in the
depositing seas, for it
is certain that most limestone has orignated from the remains of animals
and plants that secrete
calcareous material, and it is most consistent to believe that such was the
case in the present
instance, and that the distinct traces of life were mostly obliterated. This
formation occupies an
irregular belt skirting the Potsdam area. It was, doubtless, originally a
somewhat uniform band
swinging around the nucleus of the state already formed, but it has since
been eroded by
streams to its present jagged outline.
                                    ST. PETER'S SANDSTONE.
     At the close of this limestone-making period, there appears to have
been an interval of which
 we have no record, and the next chapter of the history introduces us to
another era of sand
 accumulation. The work began by the leveling up of the inequalities of the
surface of the Lower
 Magnesian limestone, and it ceased before that was entirely accomplished
in all parts of the
 State, for a few prominences were left projecting through the sand deposits.
The material laid
 down consisted of a silicious sand, of uniform, well-rounded-doubtless well-rolled-grains.
This
 was evidently deposited horizontally upon the uneven limestone surface,
and so rests in a sense
116


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