GEOLOGY OF IOWA.
Classification of Rocks-Azoic System-Huronian
Group-Lower Silurian System-Primordial
Group-Trenton Group-Cincinnati Group-Upper
Silurian System-Niagara Group Devonian
System-Hamilton Group-Carboniferous
System-Sub-Carboniferous Group Kinderhook
Beds-Burlington Limestone-Keokuk Limestone-St.
Louis Limestone Coal-Measure Group-Cretaceous
System-Nishnabotany Sandstone-Woodbury
Sandstones and Shales-Inoceramus Beds.
IN
January, 1855, the General Assembly
passed an act to provide for a geological
survey of the State. Under authority
given by this act, Prof. James
Hall, of New York, was appointed
State Geologist, and Prof. J. D.
Whitney, of Massachusetts, State
Chemist. During the years 1855, 1856,
and 1857, the work progressed, but
was confined chiefly to the eastern
counties. A large volume was published
in two parts, giving in detail the
results of the survey up to the close
of the season of 1857, when the work
was discontinued. In 1866 it was resumed
under an act of the General Assembly
passed in March of that year; and
Dr. Charles A. White, of Iowa
City. was appointed State Geologist.
He continued the work, and in December,
1869,
118
submitted a report to
the Governor in two large volumes.
From these reports we derive a pretty
thorough knowledge of the geological
characteristics in all portions of
the State.
In the classification of Iowa rocks,
State Geologist White adopted the
following definitions:
The term "formation"
is restricted to such assemblages
of strata as have been formed within
a geological epoch; the term "group,"
to such natural groups of formation
as were not formed within a geological
period; and the term "system,"
to such series of groups as were each
formed within a geological age.
The terms used
in this arrangement may be referred
to two categories one applicable to
geological objects, and the other
to geological time. Thus: Formations
constitute groups; groups constitute
Systems; Epochs constitute Periods;
periods constitute Ages.
In accordance with this arrangement
the classification of Iowa rocks may
be seen at a glance in the following
table constructed by Dr. White:
Click on image to see full size.
AZOIC SYSTEM.
Huronian
Group. - The Sioux Quartzite Formation
in this Group is found exposed in
natural ledges only on a few acres
in the northwest corner of the State.
The exposures in Iowa are principally
upon the banks of the Big Sioux river,
for which reason the specific name
of Sioux Quartzite is given to it.
It is an intensely hard rock, breaking
with a splintery fracture, and a color
varying in different localities from
a bright to a deep red. Although it
is so compact and hard the grains
of sand of which it was originally
composed are yet distinctly to be
seen, and even the ripple marks upon
its bedding surfaces are sometimes
found as distinct as they were when
the rock was a mass of incoherent
sand in the shallow waters in which
it was accumulated. The lines of stratification
are also quite distinct, but they
are not usually sufficiently definite
to cause the mass to divide into numerous
layers. It has, however, a great tendency
to break up by vertical cracks
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and fissures into small
angular ,blocks: ,The process of metamorphism
has been so complete throughout the
whole formation that the rock is almost
everywhere of uniform texture, and
its color also being so nearly uniform
there is no difficulty in identifying
it wherever it may be seen.
In a few rare
cases this rock may be quarried readily,
as the layers are easily separated,
but usually it is so compact throughout
that it is quarried with the greatest
difficulty into any forms except those
into which it naturally cracks. It
has a great tendency, however, upon
its natural exposures, to break up
by vertical fissures and cracks into
angular blocks, of convenient size
for handling. Except this tendency
to crack into angular pieces, the
rock is absolutely indestructible.
No traces of fossil remains of any
kind have been found in it. As shown
by the table its exposure in Iowa
is fifty feet in thickness.
LOWER SILURIAN SYSTEM.
Primordial
Group. - The Potsdam Sandstone
Formation of this Group has a geographical
range extending throughout the northern
portion of the United States and Canada,
and in Iowa reaches a known thickness
of about 300 feet, as shown in the
table. It forms, however, rather an
inconspicuous feature in the geology
of Iowa. It is exposed only in a small
portion of the northeastern part of
the State, and has been brought to
view there by the erosion of the river
valleys. The base of the formation
does not appear anywhere in Iowa,
consequently its full thickness is
not certainly known, nor is it known
certainly that it rests on the Sioux
Quartzite. The rock is everywhere
soft; usually a very friable sandstone,
but sometimes containing some clayey
material, and approaching in character
a sandy shale. It is nearly valueless
for any economic purpose, not being
of sufficient hardness to serve even
the commonest purposes of masonry.
No fossils have been discovered in
this formation in Iowa, but in Wisconsin
they are .found quite abundantly in
it.
The Lower Magnesian
Limestone Formation has but little
greater geographical extent in Iowa
than the Potsdam Sandstone has; because,
like that formation, it appears only
in the bluffs and valley-sides of
the same streams. It is a more conspicuous
formation, however; because, being
a firm rock, it presents bold and
often picturesque fronts along the
valleys. Its thickness is about 250
feet, and is quite uniform in composition,
being a nearly pure buff-colored dolomite.
It lacks a uniformity of texture and
stratification which causes it to
weather into rough and sometimes grotesque
shapes, as it stands out in bold relief
upon the valley-sides. It is not generally
valuable for building purposes, owing
to its lack of uniformity in texture
and bedding. Some parts of it, however,
are selected which serve for such
uses at Lansing and McGregor. It has
also been used to some extent for
making lime, but it is not equal to
the Trenton limestone, near Dubuque,
for that purpose. The only fossils
that have been found in this formation
in Iowa, are, so far as known, a few
traces of the stems of Crinoids found
near McGregor.
The St. Peter's
Sandstone Formation is remarkably
uniform in thickness throughout its
known geographical extent. It is a
clean grit, light colored, very friable
rock; so pure in its silicious compostion
[composition] that it is probable
some portions of it may be found suitable
for the manufacture of glass. It occupies
the surface of a large portion of
the north half of Allamakee county,
immediately beneath the drift, and
it is also exposed a couple of miles
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below McGregor, where it is much colored
by oxide of iron. It contains no fossils.
Trenton Group.
- The lower formation of this group
is known as the Trenton Limestone.
With the exception of this all the
limestones of both Upper and Lower
Silurian age in Iowa, are magnesian
limestones-nearly pure dolomites.
The rocks of this formation also contain
much magnesia, but a large part of
it is composed of bluish compact common
limestone. It occupies large portions
of both Winneshiek and Allamakee counties,
together with a portion of Clayton.
Its thickness as seen along the bluffs
of the Mississippi is about eighty
feet, but in Winneshiek county we
find the thickness is increased to
upward of 200 feet. The greater part
of this formation is worthless for
economic purposes, but enough of it
is suitable for building purposes
and for lime to meet the wants of
the inhabitants. The worthless portions
of the formation consists of clayey
shales and shaly limestone. Fossils
are abundant in this formation. In
some places the rock is made up of
a mass of shells, corals, and fragments
of trilobites, together with other
animal remains, cemented by calcareous
matter into compact form.
The upper portion
of the Trenton Group, known as the
Galena Limestone Formation, occupies
a narrow strip of country, seldom
exceeding 12 miles in width, but it
is fully 150 miles long. It is about
250 feet thick in the vicinity of
Dubuque, but diminishes in thickness
as it extends northwest, so that it
does not probably exceed 100 feet
where it crosses the northern boundary
of the State. The outcrop of this
formation traverses portions of the
counties of Howard, Winneshiek, Allamakee,
Fayette, Clayton, Dubuque, and Jackson,
It exhibits its greatest development
in Dubuque county; It is not very
uniform in texture, which causes it
to decompose unequally, and consequently
to present interesting forms in the
abrupt bluffs of it, which border
the valleys. It is usually unfit for
dressing, but affords good enough
stone for common masonry. It is the
source of' the lead ore of the Dubuque
lead mines. The full thickness of
this formation at Dubuque is 250 feet.
Fossils are rare in it.
Cincinnati
Group. - The Maquoketa Shale Formation
of this group, so-called by Dr. White,
is synonymous with the Hudson River
Shales, of Prof. Hall. It is comprised
within a long and narrow area, seldom
reaching more than a mile or two in
width, but, more than a hundred miles
long, in the State. Its most southerly
exposure is in the bluffs of the Mississippi
river, near Bellevue, in Jackson county,
and the most northerly one yet recognized
is in the western part of Winneshiek
county. The whole formation is largely
composed of bluish and brownish shales.
Its economic value is very slight,
as it is wholly composed of fragmentary
materials. The fossils contained in
this formation, together with its
position in relation to the underlying
and overlying formations, leave no
doubt as to the propriety of referring
it to the same geological period as
that in which the rocks -at Cincinnati,
Ohio, were formed. Sever species of
fossils which characterize the Cincinnati
group are found in the Maquoketa Shales,
but they contain a large number of
species that have been found nowhere
else than in these shales in Iowa,
and it is the opinion of Dr. White
that the occurrence of these distinct
fossils in the Iowa formation would
seem to warrant the separation of
the Maqnoketa Shales as a distinct
formation from any others of the group,
and that its true position is probably
at the base of the Cincinnati group.
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121
UPPER SILURIAN SYSTEM.
Niagara Group
- The area occupied by the Niagara
limestone Formation is nearly 160
miles from north to south, and between
40 and 50 miles wide in its widest
part. At its narrowest part, which
is near its northern limit in Iowa,
it is not more than four or five miles
wide. This formation is entirely magnesean
limestone, with, in some places, a
considerable proportion of silicious
matter in the form of chert or coarse
flint. Some of' the lower portions
resemble both the Galena and Lower
Magnesian Limestones, having the same
want of uniformity of texture and
bedding. It affords, however, a great
amount of excellent quarry rock. The
quarries at Anamosa; in Jones, county,
are remarkable for the uniformity
of the bedding of its strata. Wherever
this rock is exposed there is always
an abundance of material for common
masonry and other purposes. In some
places excellent lime is made from
it.
DEVONI.AN SYSTEM.
Hamilton Group.
- The Hamilton Limestone and Shales
Formation occupies an area of surface
as great as those occupied by all
the formations of both Lower and Upper
Silurian age in the State. The limestones
of the Devonian age are composed in
part of magnesian strata, and in part
of common limestone. A large part
of the material of this formation
is quite worthless, yet other portions
are very valuable for several economic
purposes. Having a very large geographical
extent in Iowa, it constitutes one
of the most important formations.
Wherever any part of this formation
is exposed, the common limestone portions
exist in sufficient quantity to furnish
abundant material for common lime
of excellent quality, as well as good
stone for common masonry. Some of
the beds furnish excellent material
for dressed stone, for all works requiring
strength and durability. The most
conspicuous and characteristic fossils
of this formation are brachipod mollusks
and corals.
CARBONIFEROUS SYSTEM.
The Sub-Carboniferous
Group. - This group occupies a
very large surface in Iowa. Its eastern
border passes from the northeastern
portion of Winnebago county in a southeasterly
direction, to the northern part of
Washington county. Here it makes a
broad and direct bend nearly eastward,
striking the Mississippi river at
the city of Muscatine. The southern
and western boundary of the area is
to a considerable extent the same
as that which separates it from the
coalfield. From the southern part
of Pocahontas county, It passes southeastward
to Fort Dodge, thence to Webster City,
thence to a point three or four miles
northeast of Eldora, in Hardin county,
thence southward to the middle of
the north line of Jasper county, thence
southeastward to Sigourney in Keokuk
county, thence to the northeast corner
of Jefferson county, and thence, by
sweeping a few miles eastward to the
southeast corner of Van Buren county.
The area as thus defined, is nearly
250 miles long, and from 20 to 40
miles wide. The general southerly
and westerly dip has carried the strata
of the group beneath the lower coal-measure
along the line last designated, but
after passing beneath the latter strata
for a distance of from 15 to 20 miles,
they appear again in the valley of
the Des Moines river, where they have
been bared by the erosion of that
valley.
The Kinderhook
Beds, the lowest Formation of the
sub-carboniferous group,
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presents its principal
exposures along the bluffs which border
the Mississippi and Skunk rivers,
where they form the eastern and northern
boundary of Des Moines county; along
English river in Washington county;
along Iowa river in Tama, Marshall,
Hardin and Franklin counties, and
along the Des Moines river in Humboldt
county. The southern part of the formation
in Iowa has the best development of
all in distinguishing characteristics,
but the width of area it occupies
is much greater in its northern part,
reaching a maximum width of eighty
miles. The Kinderhook formation has
considerable economic value, particularly
in the northern portion of the region
it occupies. The stone which it furnishes
is of practical value. There are no
exposures of stone of any other kind
in Pocahontas, Humboldt and some other
counties embraced in the area occupied
by it, and therefore it is of very
great value in such places for building
material. It may be manufactured into
excellent lime. The quarries in Marshall
county and at Le Grand are of this
formation; also the oolitic limestone
in Tama county. This oolitic limestone
is manufactured into a good quality
of lime. The principal fossils appearing
in this formation are the remains
of fishes; no remains of vegetation
have as yet been detected. The fossils
in this formation, so far as Iowa
is concerned, are far more numerous
in the southern than in the northern
part.
Burlington Limestone
is the next Formation in this group
above the Kinderhook Beds, the latter
passing gradually into the Burlington
Limestone. This formation consists
of two distinct calcareous divisions,
which are operated by a series of
silicious beds. The existence of these
silicious beds suggests the propriety
of regarding the Burlington Limestone
as really two distinct formations.
This is strengthened also by some
well marked palaeontological differences,
especially in the crinoidal remains.
The southerly dip of the Iowa rocks
carries the Burlington Limestone down,
so that it is seen for the last time
in this State in the valley of Skunk
river, near the southern boundary
of Des Moines county. Northward of
Burlington it is found frequently
exposed in the bluffs of the Mississippi
and Iowa rivers in the counties of
Des Moines and Louisa, and along some
of the smaller streams in the same
region. Burlington Limestone forms
a good building material; good lime
may also be made from it, and especially
from the upper division. Geologists
have given to this formation the name
of Burlington Limestone because its
peculiar characteristics are best
shown at the city of Burlington, Iowa.
The great abundance and variety of
its characteristic fossils-crinoids
-- have attracted the attention of
geologists and naturalists generally.
The only remains of vertebrates reported
as being found in it are those of
fishes. Remains of articulates are
rare in it, and confined to two species
of trilobites. Fossil shells are common
but not so abundant as in some of
the other formations of the Sub-Carboniferous
Group.
The Keokuk Limestone
is the next Formation in this group
above the Burlington Limestone. In
Iowa it consists of about fifty feet
in maximum thickness. It is a grayish
limestone, having usually a blueish
tinge. It occupies in Iowa a. more
limited area than any other formation
of the sub-carboniferous group. It
is well developed and largely exposed
at the city of Keokuk. It is synonymous
with the Lower Archimedes Limestone
of Owen and other geologists. The
most northerly point at which it has
been recognized is in the northern
part of Des Moines county, where it
is quite thinned out. It is only in
the counties of Lee, Van Buren, Henry
and Des Moines that the Keokuk Limestone
is to be seen; but it rises again
and is
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seen in the banks of
the Mississippi river some seventy-five
or eighty miles below Keokuk, presenting
there the same characteristics that
it has in Iowa. The upper silicious
portion of this formation is known
as the Geode bed. These geodes are
more or less spherical masses of silex,
usually hollow and lined with crystals
of quartz. The Keokuk Limestone formation
is of great economic value, as some
of its layers furnish a fine quality
of building material. The principal
quarries of it are along the Mississippi
from Keokuk to Nauvoo, a distance
of about fifteen miles. The only vertebrated
fossils in it are those of fishes,
consisting both of teeth and spines.
Some of these are of great size, indicating
that their owners probably reached
a length of twenty-five or thirty
feet. Several species of articulates,
mollusks and radiates are also found
in this formation. Among the radiates
the crinoids are very abundant, but
are not so conspicuous as in the Burlington
Limestone. A small number of Protozoans,
a low form of animal life, related
to sponges, have also been found in
the Keokuk Limestone.
The next Formation
in the Sub-Carboniferous Group, above
the Keokuk Limestone, is what Dr.
White calls the St. Louis Limestone,
and is synonymous with the Concretionary
Limestone of Prof. Owen, and the Warsaw
Limestone of Prof. Hall. It is the
upper, or highest formation of what
Dr. White classifies as the Sub-Carboniferous
Group, appearing in Iowa, where the
lower coal-measures are usually found
resting directly upon it, and where
it forms, so to speak, a limestone
floor for the coal-bearing formations.
To this, however, there are some exceptions.
It presents a marked contrast with
the coal-bearing strata which rest
upon it. This formation occupies a
small superficial area in Iowa, because
it consists of long narrow strips.
Its extent, however, within the State
is known to be very great, because
it is found at points so distant from
each other. Commencing at Keokuk,
where it is seen resting on the geode
division of the Keokuk limestone,
and proceeding northward, it is found
forming a narrow border along the
edge of the coal-field in Lee, Des
Moines, Henry, Jefferson, Washington,
Keokuk and Mahaska counties. It is
then lost sight of beneath the coal-measure
strata and overlying drift until we
reach Hamilton county, where it is
found in the banks of Boone river
with the coal-measures resting upon
it, as they do in the counties just
named. The next seen of the formation
is in the banks of the Des Moines
river at and near Fort Dodge. These
two last named localities are the
most northerly ones at which the formation
is exposed, and they are widely isolated
from the principal portion of the
area it occupies in Iowa; between
which area, however, and those northerly
points, it appears by a small exposure
near Ames, in Story county, in the
valley of a small tributary of Skunk
river. This formation as it appears
in Iowa, consists of three quite distinct
sub-divisions-magnisian, arenaceous
and calcareous, consisting in the
order named of the lower, middle and
upper subdivisions of the formation.
The upper division furnishes excellent
material for quicklime, and in places
it is quarried to serve a good purpose
for masonry. The middle division is
of little economic value, being usually
too soft for practical use. The lower,
or magnesian division, furnishes some
excellent stone for heavy masonry,
and has proved to be very durable.
This formation has some well marked
fossil characteristics, but they do
not stand out with such prominence
as some of those in the two preceding
formations. The vertibrates, articulates,
mollusks, and radiates, are all more
or less represented in it. Some slight
vegetable remains have also been detected
in it.
The Coal-measure
Group.-The formations of this group
are divided
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124
into the Lower, Middle,
and Upper Coal-measures. Omitting
particular reference to the other
strata of the Lower Coal-measure,
we refer only to the coal which this
formation contains. Far the greater
part of that indispensable element
of material prosperity is contained
in the strata of the Lower Coal-measures.
Beds are now being mined in this formation
that reach to the thickness of seven
feet of solid coal. Natural exposures
of this formation are few, but coal
strata are being mined in a number
of localities.
The area occupied by the Middle Coal-measure
is smaller than that of either of
the others, and constitutes a narrow
region between them. The passage of
the strata of the Lower with the Middle
Coal-measure is not marked by any
well defined line of division.
The area occupied
by the Upper Coal-measure formation
in Iowa is very great, comprising
thirteen whole counties in the southwestern
part of the State, together with parts
of seven or eight others adjoining.
It adjoins by its northern and eastern
boundary the area occupied by the
Middle Coal-measures. The western
and southern limits in Iowa of the
Upper Coal-measures are the western
and southern boundaries of the State,
but the formation extends without
interruption far into the States of
Missouri. Nebraska and Kansas. It
contains but a single bed of true
coal, and that very thin. Its principal
economic value is confined to its
limestone. Wherever this stone is
exposed it furnishes good material
for masonry, and also for lime. The
prevailing color of the limestone
is light gray, with usually a tinge
of blue. The sandstones of this formation
are usually shaly, and quite worthless.
CRETACEOUS SYSTEM.
The Nishnabotany
Sandstone. - This formation is
well exposed in the valley of the
East Nishnabotany river, from which
circumstance Dr. White has so named
it. It is found as far east as the
southeastern part of Guthrie county,
and as far south as the southern part
of Montgomery county. To the northwestward
it passes beneath the Woodbury sandstones
and shales, the latter in turn passing
beneath the Inoceramus; or chalky
beds. It reaches a maximum thickness
in Iowa, so far as known, of about
100 feet, but the exposures usually
show a much less thickness. It is
a soft sandstone, and, with few exceptions,
almost valueless for economic purposes.
The most valuable quarries in the
strata of this formation, so far as
known, are at Lewis, Cass county,
and in the northeastern part of Mills
county. Several buildings have been
constructed of it at Lewis, but with
some the color is objectionable, being
of a dark brown color. A few fossils
have been found in it, being leaves
too fragmentary for identification.
The Woodbury
Sandstones and Shales. - These
are composed of alternating sandstones
and shales, as the name implies, and
rest upon the Nishnabotany sandstone.
They have not been observed outside
of the limits of Woodbury county,
but they are found there to reach
a maximum of about 150 feet. Some
layers are firm and compact, but the
larger part is impure and shaly. The
best of it is suitable for only common
masonry, but it furnishes the only
material of that kind in that part
of the State. Some slight fossil remains
have been found in this formation.
The Inoceramus
Beds. - These beds constitute
the upper formation of the Cretaceous
System in Iowa, and have a maximum
thickness of about 50 feet they rest
directly upon the Woodbury sandstones
and shales. They are
125
observed nowhere in
Iowa except along the bluffs of the
Big Sioux river, in Woodbury and Plymouth
counties. They are composed of calcareous
material, but are not a true, compact
limestone. The material of the upper
portion is used for lime, the quality
of which is equal to that of common
limestone. No good building material
is obtained from these beds. Some
fossil fish have been found in them.
Above all the
formations above-mentioned rests the
Post-Tertiary, or Drift deposit, which
is more fully mentioned in connection
with the Soils of Iowa.
ECONOMIC GEOLOGY.
Coal-Peat - Building Stone-Lime-Lead-Gypsum-Spring
and Well Water-Clays
Mineral Paint.
COAL.
Every year is
adding to our knowledge of, and attesting
the importance and value of our vast
coal deposits. In some unknown age
of the past, long before the history
of our race began, Nature by some
wise process, made a bountiful provision
for the time when, in the order of
things, it should become necessary
for civilized man to take possession
of these broad rich prairies. As an
equivalent for the lack of trees,
she quietly stored away beneath the
soil those wonderful carboniferous
treasures for the use and comfort
of man at the proper time. The increased
demand for coal has in many portions
of the State led to improved methods
of mining, so that in many counties
the business is becoming a lucrative
and important one, especially where
railroads furnish the means of transportation.
The coal field of the State embraces
an area of at least 20,000 square
miles, and coal is successfully mined
in about thirty counties, embracing
a territory larger than the State
of Massachusetts. Among the most important
coal producing counties may be mentioned
Appanoose, Boone, Davis, Jefferson,
Mahaska, Marion, Monroe, Polk, Van
Buren, Wapello, and Webster. Within
the last few years many discoveries
of new deposits have been made, and
counties not previously numbered among
the coal counties of the State are
now yielding rich returns to the miner.
Among these may be mentioned the counties
of Boone, Dallas, Hamilton, Hardin,
and Webster. A vein of coal of excellent
quality, seven feet in thickness,
has been opened, and is now being
successfully worked, about five miles
southeast of Fort Dodge, in Webster
county. Large quantities of coal are
shipped from that point to Dubuque
and the towns along the line of the
Dubuque and Sioux City Railroad. A
few years ago it was barely known
that some coal existed in Boone county,
as indicated by exposures along the
Des Moines river, and it is only within
the last few years that the coal mines
of Moingona have furnished the vast
supplies shipped along the Chicago
and Northwestern Railroad, both east
and west. The great productive coal
field of Iowa is embraced chiefly
within the valley of the Des Moines
river and its tributaries, extending
up the valley from Lee county nearly
to the north line of Webster county.
Within the coal field embraced by
this valley deep mining is nowhere
necessary. The Des Moines and its
larger tributaries have generally
cut their channels down through the
coal measure strata.
The coal of Iowa
is of the class known as bituminous,
and is equal in quality and value
to coal of the same class in other
parts of the world. The veins which
have so tin been worked are from three
to eight feet in
126
thickness, but we do
not have to dig from one thousand
to two thousand feet to reach, the
coal, as miners are obliged to do
in some countries. But little coal
has in this State been raised from
a depth greater than one hundred feet.
Click on image
for full view
Prof. Gustavus Hinrich,
of the State University, who also
officiated as State Chemist in the
prosecution of the recent Geological
Survey, gives an analysis showing-
the comparative value of Iowa coal
with that of other countries. The
following is from a table prepared
by him-100 representing the combustible:
In this table
the excess of the equivalent above
100, expresses the amount of impurities
(ashes and moisture) in the coal.
The analysis shows that the average
Iowa coals contains only ten parts
of impurities for one hundred parts
combustible (carbon and bitumen),
being the purest of all the samples
analyzed, except the Anthracite from
Pennsylvania.
PEAT.
Extensive
deposits of peat in several of the
northern counties of Iowa have attracted
considerable attention. In 1866, Dr.
White, the State Geologist, made careful
observations in some of those counties,
including Franklin, Wright, Cerro
Gordo, Hancock, Winnebago, Worth,
and Kossuth. It is estimated that
the counties above named contain an
average of at least four thousand
acres each of good peat lands. The
depth of the beds are from four to
ten feet, and the quality is but little,
if any, inferior to that of Ireland.
As yet, but little use has been made
of it as a fuel, but when it is considered
that it lies wholly beyond the coal-field,
in a sparsely timbered region of the
State, its prospective value is regarded
as very great. Dr. White estimates
that 160 acres of peat, four feet
deep, will supply two hundred and
thirteen families with fuel for upward
of twenty-five years. It must not
be inferred that the presence of these
peat beds in that part of the State
is in any degree prejudicial to health,
for such is not the case. The dry
rolling prairie land usually comes
up to the very border of the peat
marsh, and the winds, or breezes,
which prevail through the summer season,
do not allow water to become stagnant.
Nature seems to have designed these
peat deposits to supply the deficiency
of other material for fuel. The penetration
of this portion of the State by railroads,
and the rapid growth of timber may
leave a resort to peat for fuel as
a matter of choice, and not of necessity.
It therefore remains to be seen of
what economic value in the future
the peat beds of Iowa may be. Peat
has also been found in Muscatine,
Linn, Clinton, and other eastern and
southern counties of the State, but
the fertile region of
top
127
Northern Iowa, least
favored with other kinds of fuel,
is peculiarly the peat region of the
State.
BUILDING STONE.
There
is no scarcity of good building stone
to be found along nearly all the streams
east of the Des Moines river, and
along that stream from its mouth up
to the north line of Humboldt county.
Some of the counties west of the Des
Moines, as Cass and Madison, as well
as most of the southern counties of
the State, are supplied with good
building stone. Building stone of
peculiarly fine quality is quarried
at and ,near the following places:
Keosauqua, Van Buren county; Mt. Pleasant,
Henry county; Fairfield, Jefferson
county; Ottumwa, Wapello county; Winterset,
Madison county; Ft. Dodge, Webster
county; Springvale and Dakota, Humboldt
county; Marshalltown, Marshall county;
Oxford, Tama county; Vinton, Benton
county; Charles City, Floyd county;
Mason City, Cerro Gordo county; Mitchell
and Osage, Mitchell county; Anamosa,
Jones county; Iowa Falls, Hardin county;
Hampton, Franklin county; and at nearly
all points along the Mississippi river.
In some places, as in Marshall and
Tama counties, several species of
marble are found, which are susceptible
of the finest finish, and are very
beautiful.
LIME;
Good
material for the manufacture of quick-lime
is found in abundance in nearly all
parts of the State. Even in the northwestern
counties, where there are but few
exposures of rock "in place,"
limestone is found among the boulders
scattered over the prairies and about
the lakes. So abundant is, limestone
suitable for the manufacture of quick-lime,
that it is needless to mention any
particular locality as possessing
superior advantages in furnishing
this useful building material. At
the following points parties have,
been engaged somewhat extensively
in the manufacture of lime, to-wit:
Ft. Dodge, Webster county; Springvale,
Humboldt county; Oxford and Indiantown,
Tama county; Iowa Falls, Hardin county;
Mitchell, Mitchell county; and at
nearly all the towns along the streams
northeast of Cedar river.
LEAD.
Long
before the permanent settlement of
Iowa by the whites lead was mined
at Dubuque by Julien Dubuque and others,
and the business is still carried
on successfully. From four to six
million pounds of ore have been smelted
annually at the Dubuque mines, yielding
from 68 to 70 per cent of lead. So
far as known, the lead deposits of
Iowa that may be profitably worked,
are confined to a belt four or five
miles in width along the Mississippi
above and below the city of Dubuque.
GYPSUM.
One of the finest and
purest deposits of gypsum known in
the world exists at Fort Dodge in
this State. It is confined to an area
of about six by three miles on both
sides of the Des Moines river, and
is found to be from twenty-five to
thirty feet in thickness. The main
deposit is of uniform gray color,
128
but large masses of
almost pure white (resembling alabaster)
have been found embedded in the main
deposits. The quantity of this article
is practically inexhaustible, and
the time will certainly come when
it will be a source of' wealth to
that part of the State. It has been
used to a considerable extent in the
manufacture of Plaster- of-Paris,
and has been found equal to the best
in quality. It has also been used
to a limited extent for paving and
building purposes.
SPRING AIND WELL WATER.
As
before stated, the surface of Iowa
is generally drained: by the rolling
or undulating character of the country,
and the numerous streams, large and
small. This fact might lead some to
suppose that it might be difficult
to procure good spring or well water
for domestic uses. Such, however,
is not the case, for good pure well
water is easily obtained all over
the State, even on the highest prairies.
It is rarely necessary to dig more
than thirty feet deep to find an abundance
of that most indispensible [indispensable]
element, good water.
Along the streams
are found many springs breaking out
from the banks, affording a constant
supply of pure water. As a rule, it
is necessary to dig deeper for well
water in the timber portions of the
State, than on the prairies. Nearly
all the spring and well waters of
the State contain a small proportion
of lime, as they do in the Eastern
and Middle States. There are some
springs which contain mineral properties,
similar to the springs often resorted
to by invalids and others in other
States. In Davis county there are
some "Salt Springs," as
they are commonly called, the water
being found to contain a considerable
amount of common salt, sulphuric acid,
and other mineral ingredients. Mineral
waters are found in different parts
of the State. No one need apprehend
any difficulty about finding in all
parts of Iowa an abundant supply of
good wholesome water.
CLAYS.
In
nearly all parts of the State the
material suitable for the manufacture
of brick is found in abundance. Sand
is obtained in the bluffs along the
streams and in their beds. Potter's
clay, and fire-clay suitable for fire-brick,
are found in many places. An excellent
article of fire-brick is made at Eldora,
Hardin county, where there are several
extensive potteries in operation.
Fire-clay, is usually found underlying
the coal-seams. There are extensive
potteries in operation in the counties
of Lee, Van Buren, Des Moines, Wapello,
Boone, Hamilton, Hardin, and perhaps
others.
MINERAL PAINT.
In
Montgomery county a fine vein of clay,
containing a large proportion of ochre,
was several years ago discovered,
and has been extensively used in that
part of the State for painting barns
and out-houses. It is of a dark red
color, and is believed to be equal
in quality, if properly manufactured,
to the mineral paints imported .from
other States. The use of it was first
introduced by Mr. J. B. Packard,
of Red Oak, on whose land there is
an extensive deposit of this material.
129
A Prairie Home
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