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CHAPTER 1
(Pictures included with this chapter are: Boulder in
Buchanan County - Glacial Marking on Rocks, Des Moines County)
Nature's supreme laws of never ending change from one degree of
development to another, seem to pervade the universe. Man in all
ages has been slowly reading these immutable statutes, unwritten,
and only to be known through careful observation and patient
investigation.
A little gained by one generation handed down to another, since
the first appearance of man upon the earth, has made the sum of
human knowledge. For how many ages on some other far off planet
human intellect has been slowly pursuing the same great study we
have no means of knowing.
Here the astronomer has discovered the existence of other worlds,
has carefully computed their size, has measured their distance from
the earth and each other, has observed their motion, their
satellites, and learned some of the laws which govern them. He has
even constructed a plausible theory as to how these planets were
formed from the original elements.
As to the comparative antiquity of the eastern and western
continents of our own earth, recent investigation brings evidence to
reverse the old belief that Asia and Africa were earlier formations
than America. Agassiz says:
"First born among the continents,
though so much later in culture and civilization than some of more
recent birth, America, so far as her physical history is concerned,
has been falsely denominated the 'new world.' Hers was the first
dry land lifted out of the waters; here the first shores washed by
the ocean that enveloped all the earth besides; and while Europe was
represented only by islands rising here and there above the sea,
America already stretched one unbroken line of land from Nova Scotia
to the far west."
In our limited world the investigators have explored the beds of
ancient rivers, lakes and seas; the caverns of rocks and mountains,
and penetrated deep into the earth in search of knowledge that may
be derived from rock formations, animal and vegetable fossils.
These to the scientist reveal much of the story of earth's growth;
its stages of development; its desolations and changes through the
agencies of fire, water and air. In these reservoirs have been
found keys to earth’s prehistoric changes. They reveal to the
student a history of its geological growth, vegetable and animal
development for millions of years before written history begins.
Scientists explore every known country, every island of the ocean,
examine rocks, clays, gravels and fossils in pursuit of knowledge of
the past. From these they read much of the story of the earliest
formations, convulsions, growth and population of the earth with
almost as much certainty as though the events had been inscribed in
legible characters on imperishable tablets. If is from these
evidences that we learn some of the history of the remote past,
relating to the land we live in, which men have named Iowa.
Professor Samuel Calvin has well said:
"The finding of a single genuine
prehistoric arrow-point may enable us to write up an important
chapter in the history of a people that no historian ever saw, and
concerning whose existence there is not even the shadow of a human
tradition. When, as is often possible, we may add the knowledge
gained by exploring their homes, their shrines and sepulchers, we
are in a position to write up somewhat more fully the portion of
their history which deals with their daily occupations and their
domestic life. Many records tell of other facts than the mere
presence of human occupants in a region such as Iowa. Vegetable
remains preserved in peat bogs in the mud that accumulated at the
bottom of ancient ponds and lakes enable us to reconstruct the
prehistoric forests. With such vegetable remains are usually found
bones of the animals that lived in the forests. Human weapons or
human skeletons are often there too. So in records preserved in the
peat bog or in the lake bed, science may rehabilitate in a general
way the prehistoric landscapes, and may see them enlivened with
multitudes of struggling creatures, man among the rest; all bent on
accomplishing the two great objects for which living things below
the higher planes of humanity seem to strive,-' to eat and to escape
being eaten.' Not only may we restore the forests in the shadow of
which prehistoric man lived, we may know the size and habits of the
animals that roamed through the forest; those that man chased and
those from which he in turn fled; we may even go farther and
determine the climatic conditions under which all this assemblage of
animal and plant life existed."
Geology unfolds to us a wonderful history of the most remote
periods of time, which reduced to language reads like a fairy tale.
It tells us nearly all we know of the countless years that passed
away while the continent, of which Iowa is a part, was in the
process of formation. Professor Calvin continues:
"These geologic records, untampered
with, and unimpeachable, declare that for uncounted years Iowa,
together with the great valley of the Mississippi, lay beneath the
level of the sea. So far as it was inhabited at all, marine forms
of animals and plants were its only occupants."
During the ages of submergence, the sedimentary strata of Iowa,
as well as of all the adjacent States, was being formed on the sea
bottom. This formation contains a record of a period of duration
altogether incomprehensible. Centuries pass while the light colored
limestones so well represented at Anamosa are slowly forming by an
imperceptible sedimentary accumulation. Other ages come and go
while the limestones represented in Johnson County are forming.
About this time a small portion of northeastern Iowa rises above
the sea, while all the vast region south and west is still buried
deep beneath the all pervading water. Odd shaped fishes and a
species of ferns mark the highest point reached in the evolution of
animal and plant life at this time.
Ages again go by while the sediment of the sea is forming beds of
rock which appear in Marshall, Des Moines and Lee counties. Then
slowly come the Coal measures and rocks above them. Ferns and
air-breathing creatures have made their appearance. The sea
gradually recedes to the southward and the surface of our whole
State is visible. Later forests and other forms of vegetation cover
portions of the land; birds appear in the woods and a few small
rat-like animals are found, as well as reptiles.
But another great change comes; the waters again cover the
northwestern portion of the State and ages come and go before the
sea recedes, never to return. Iowa has finally been raised above
the sea level and the waters drain toward the ocean, forming great
rivers, and plowing deep channels through the oozing sediment. The
sun and wind finally dry the surface; forests and rank vegetation
again make their appearance; animals come forth from Nature's
nurseries and spread themselves over the land, and roam through the
jungles, preying upon each other in their struggle for food. The
climate is that of the tropics, and myriads of forms of life are
evolved.
All of the conditions are now favorable for the advent of man,
but no evidence is found of his existence on any portion of the
earth at this period. The rivers, which ages later were named the
Mississippi and Missouri, were then carrying the inland waters to
the sea which reached as far north as the Ohio river.
Where the upper Missouri now flows through the prairies of
Nebraska, the Dakotas and Montana, where lakes spreading over a
large portion of these States. Remains of forests and strange
species of animals, long since extinct, have been found in the
sediment that was formed in these lakes. Tropical trees such as the
cypress, magnolia, cinnamon, fig and palm flourished in Iowa,
Dakota, and far northward into British America; tropical birds sang
in the forests; huge reptiles crawled about in the rank vegetation
and swamps.
Then came the Tertiary period. Iowa was a part of the land area
which then made up the half formed continent of North America. The
drainage of the State must have been much the same as now, although
the altitude above sea level was several hundred feet lower.
In the beds of Tertiary lakes were entombed animals and plant
remains which man in these late generations has found. The sediment
exposed to the action of the atmosphere has been converted into vast
plains and prairies. In many cases the lakes have been gradually
filled and converted into dry land. Modern streams, such as the
Yellowstone, Missouri and the Platte rivers cut their way through
these old lake beds. The surface of the sediment underwent
continual changes through erosion. The remains of plants and
animals were thus slowly laid bare, and the scientist was able to
read the story of their lives. Such beds are believed to be the
only places of importance where the records of Tertiary plants and
animals have been preserved. While none of these lake beds have
been found within the limits of our State, it cannot be doubted that
the conditions which prevailed upon our western and northern
boundaries were not unlike those which obtained here.
The animal inhabitants of this period consisted of opossums, a
strange species of squirrel, beavers and gophers. There were large
hoofed animals not unlike the rhinoceros; others bore resemblance to
the tapir and the swine family. There were creatures with three
hoofs to each foot and three toes on each hoof, of a species related
to the horse. There were others resembling camels, oxen and
cud-chewing animals that seemed to be a combination of the deer, the
camel and the hog. There was a family of short jawed animals
resembling the panther with sharp, knife-like teeth. There were
saber-toothed tigers more powerful and cruel than the Asiatic
species; there were monkeys, foxes and wolves. Huge snakes, lizards
and turtles infested the swamps. Bright winged birds flitted among
the forests and open glades. Bats and myriads of strange insects
were present preying upon others.
Throughout the Tertiary period the climatic conditions appear to
have been remarkably uniform over regions extending north to
Greenland and westward to Montana. Iowa, and all adjacent regions
far north and westward reveled in the luxuriance of a tropical
climate. The air was balmy and laden with the odor of flowers and
fruits. The bright summer days seemed never ending. A listless
languor sent the birds and beasts into the shade at midday.
Tropical vegetation grew spontaneously; brilliant foliage and
flowers, luxuriant ferns and clinging vines mingled with the forests
and open vistas in landscapes of surpassing beauty.
But in the course of time a change was perceptible. The intense
heat of the long summer days was tempered by refreshing breezes, and
the nights became delightfully cool. The winters were slowly
growing colder. Snow storms came and piercing winds swept over
plain and forest. Tropical plants were stricken with early frosts;
ice formed in lakes and streams where it had never had before
appeared. The more hardy animals sought the shelter of wooded
ravines and deep gorges. Snow fell to unusual depths; year after
year it came earlier, and winter continued later. The earth became
frozen to great depths; fruits and trees disappeared. As the snow
piled higher each succeeding year, and the summers were too short
and cold to melt it, all animal life perished. The pressure of
mountains of snow and the percolating rains converted the mass into
a solid sheet of glacier ice that not only covered nearly all of
Iowa, but reached out over the northern half of North America.
The ice sheet of this period had its southern margin south of the
latitude of St. Louis. The ice was slowly moving outward from the
center of accumulation, grinding over the underlying rocks, crushing
them into the finest powder. Fragments of enormous size were
frequently caught in the lower portion of the flowing ice and
carried forward bodily, grinding the rock strata into rock flour,
and being themselves planed and grooved on the lower surface. All
boulders of crystalline rock which we find strewn over our State
were carried from their native ledges in British America by these
ice sheets of what geologists call the Quaternary period.
Another climatic change slowly came, and the ice began to melt.
Rivers were gradually formed, carrying on their turbid waters the
soil made by the grinding ice. This was deposited over the surface
of the State, forming yellow clay.
Professor Samuel Calvin, State Geologist for Iowa, has told how
the soils of the State were produced by the action of the ice in the
glacial period. He says:
"Glaciers and glacial action have
contributed in a very large degree to the making of our magnificent
state. What Iowa would have been had it never suffered from the
effects of the ponderous ice sheets that successfully overflowed its
surface, is illustrated, but not perfectly, in the driftless area.
Here we have an area that was not invaded by glaciers. Allamakee,
parts of Jackson, Dubuque, Clayton, Fayette, and Winneshiek counties
belong to the driftless area. During the last two decades numerous
wells have been bored through the loose surface deposits, and down
into the underlying rocks. The record of these wells shows that the
rocks surface is very uneven. Before the glacial drift which now
mantles nearly the whole of Iowa was deposited, the surface had been
carved into the intricate of hills and valleys.
"To a person passing from the
drift-covered to the driftless part of the state the topography
presents a series of surprises. The principal drainage streams flow
in valleys that measure, from the summits to the divides, six
hundred feet or more in depth. The Oneota, or upper Iowa River, in
Allamakee County, for example, flows between picturesque cliffs that
rise almost vertically from three to four hundred feet, while from
the summit of the cliffs the land rises gradually to the crest of
the divide, three, four, or five miles back from the stream.
Tributary streams cut the lateral slopes and canyon walls at
intervals. These again have tributaries of the second order. In
such a region a quarter section of level land would be a curiosity.
This is a fair sample of what Iowa would have been had it not been
planed down by the leveling effects of the glaciers. Soils of
uniforms excellence would have been impossible in a non-glacial
Iowa. The soils of Iowa have a value equal to all of the silver and
gold mines of the world combined.
"And for this rich heritage of
soils we are indebted to great rivers of ice that overflowed Iowa
from the north and northwest. The glaciers in their long journey
ground up the rocks over which they moved and mingled the fresh rock
flour from granites of British America and northern Minnesota with
pulverized limestones and shales of more southern regions, and used
these rich minerals in covering up the bald rocks and leveling the
irregular surface of preglacial Iowa. The materials are in places
hundreds of feet in depth. They are not oxidized or leached, but
retain the carbonates and other soluble constituents that contribute
so large to the growth of plants. The physical condition of the
materials is ideal, rendering the soil porous, facilitating the
distribution of moisture, and offering unmatched opportunities for
the employment of improved machinery in all of the processes
connected with cultivation. Even the driftless area received great
benefit from the action of glacier, for although the area was not
invaded by ice, it was yet to a large extent covered by a peculiar
deposit called loess, which is generally connected with one of the
later sheets of drift. The loess is a porous clay, rich in
carbonate of lime. Throughout the driftless area it has covered up
many spots that would otherwise have been bare rocks. It covered
the stiff intractable clays that would otherwise have been the only
soils of the region. It in itself constitutes a soil of great
fertility. Every part of Iowa is debtor in some way to the great
ice sheets of the glacial period.
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"Soils are everywhere the product
of rock disintegration, and so the quality of the soils in a given
locality must necessarily be determined in large measure by the kind
of rock from which they were derived.
"From this point of view therefore,
the history of Iowa's superb soils begin with first steps in rock
making. The very oldest rocks of the Mississippi Valley have
contributed something to making our soils to what they are, and
every later formation laid down the surfaces of Iowa, or regions
north of it, has furnished its quota of materials to the same end.
The history of Iowa's soils, therefore, embraces the whole sweep of
geologic times.
"The chief agents concerned in
modifying the surface throughout most of Iowa since the
disappearance of the latest glaciers have been organic, although the
physical and chemical influences of air have not been without marked
effect. The growth and decay of a long series of generations of
plants have contributed certain organic constituents to the soil.
Earth worms bring up the material from certain depths and place it
in position to spread upon the surface. They drag leaves and any
manageable plants into their burrows, and much of the material so
much taken into the ground decays and enriches the ground to a depth
of several inches. The pocket gopher has done much to furnish a
surface area of loose, mellow, easily cultivated and highly
productive soil. Like the earth worm, the gopher for century after
century has been bringing up to the surface fine material, to the
amount of several tons annually to the acre, avoiding necessarily
the pebbles, cobbles and coarser constituents. The burrows
collapse, the undermined boulders and large fragments sink
downwards, rains and winds spread out the gopher hills and worm
castings, and the next year and the next, the process is repeated;
and so it has been for all the years making up the centuries since
the close of the glacial epoch. Organic agents in the form of
plants and burrowing animals have worked unremittingly through many
centuries and accomplished a work of incalculable value in
pulverizing, mellowing and enriching the superficial stratum, and
bringing it to the ideal condition to which it was found by the
explorers and pioneers from whose extent dates the historical period
of our matchless Iowa.
It is estimated that the last invasion of Iowa by the glaciers
was from 100,000 to 170,000 years ago. For many years scientists
have been investigating the causes which have produced the great
treeless plains of the Mississippi Valley. East of Ohio prairies
are unknown, but as we go westward they increase in number and size.
In western Indiana, and from there to the Rocky Mountains west and
north the vast prairies* prevail, although groves are often found,
and the margins of lakes, rivers and creeks are generally bordered
with the same extent as trees. From 98' of longitude west and
treeless plains become almost a desert.
* Prairie is a French word
signifying meadow. It was first applied to the great treeless
plains of North America by the French missionaries who were the
discoverers of the prairie regions of the west.
The soil of prairies varies in formation and quality to almost as
great an extent as in the timbered regions. In Michigan, Indiana and
Illinois the prairies are inclined to be quite level, the surface
soil is a black vegetable formation to six inches to five feet or
more in depth. In Iowa the prairies are more rolling, affording
better surface drainage.
In southern Wisconsin, Minnesota, the Dakotas, western Nebraska,
northern Missouri, and western Kansas, the vegetable formation is
lighter, sand and gravel being quite common on the surface.
Along the first river bottoms, the soil is generally a deep rich
alluvium. The second bench often presents a mixture of sand and
gravel while the bluffs show soil of a lighter color, with clay near
the surface. Large bodies of broken land, cut up into steep hills,
generally extend back from the water courses, through which deep
ravines have been cut in all directions. This land is generally
covered to some extent with growth of stunted oak and hickory trees,
among which are thickets of wild plum, crab apple and hazel bushes.
These lands were called "barrens' by the early settlers. The soil
of this hill land is productive, producing grain, grass and fruit of
excellent quality. The "Missouri slope" is the name given to that
portion of Iowa which is drained into the Missouri River. The soil
is a bluff deposit, generally destitute of surface stone and gravel,
or rock strata beneath, and produces excellent crops of grain,
grass, vegetables and fruit. The bluffs along the Mississippi River
rise to a height of from one to two hundred feet, everywhere
intersected with deep ravines. They are generally treeless, but in
some places small timber is found. Northern Iowa is but gently
rolling fifty miles west of the Mississippi, while the southern half
of the state is more broken into hills and valleys, and has large
tracts of woodland.
Although essentially a prairie state, almost every variety of
surface soil is found, showing conclusively that it is not the
peculiar soil formation which causes forests to grow in one locality
and prairies to be found intermingled with them.
After more than half a century of investigation of the causes
which have produced the prairies, the problem is yet unsettled. No
theory yet advanced explain satisfactorily why the treeless plains
begin in certain sections of Michigan, Indiana, Wisconsin, Missouri,
Kansas and Louisiana, without any noticeable difference in soil or
surface. In many places in the states where the prairies
predominate, remains of forests are found that show evidences of
having existed for hundreds of years, and among the mare prairies
which furnish no indications of ever having been covered with trees.
The origin of the prairies is one of the most interesting problems
that has engaged the attention of all thoughtful people who have
seen them before they were touched by the plow. Scientists have
sought carefully for evidences to sustain the different theories
advanced. Professors Whitney and Hall, who made early geological
surveys and examinations of portions of Iowa, gave considerable
attention to the origin of prairies. Whitney says:
"The cause of the absence of trees
on the prairies, is the physical character of the soil, and
especially its exceeding fineness, which is prejudicial to the
growth of anything but a superficial vegetation. The smallness of
the particles of soil being an insuperable barrier to the necessary
access of air to the roots of deeply rooted vegetation. Wherever,
in the midst of the extraordinary fine soil of the prairies, coarse
and gravelly patches exist, there dense forests occur. The theory
that fineness of soil is fatal to tree growth finds its most
remarkable support in the fact that in southeast Russia the limits
of the black soil of Russia is an earth of exceeding fineness, so
fine indeed that it is with the greatest difficulty that the air can
penetrate it so as to oxidize the organic matter which it contains.
It is easy to see why plains are likelier than mountain slopes to
be treeless, it being toward the plains that the finer particles of
the material which is abraded from the higher regions is being
constantly carried. The more distant the region from the mountains,
and the broader its area, the more likely it is that a considerable
portion of it will be covered with a fine detritus, whether this be
of sub-aerial origin, or deposited at the bottom of the sea.
"The exceedingly fine soil of the
typical prairie region consists in large part of the residual
materials left after the removal by percolation of rain and other
atmospheric agencies of the calcareous portion of the undisturbed
stratified deposits, chiefly of the Paleozoic age, which underlies
so large a portion of the Mississippi Valley. The finer portions of
the formations of more recent age in the Gulf States have also over
considerable area remained treeless."
Professor James Hall says:
"Throughout the prairie regions the
underlying rocks are soft sedimentary strata, especially shale’s and
impure limestones. Most of these on exposure disintegrate readily
and crumble to soil. The whole soil of the prairies appears to have
been produced from such materials, not far removed from their
present beds. The valley soil, containing a larger portion of
coarse materials than that of the uplands, seems to have been
adapted to the growth of forest vegetation. In consequence of this
we find such localities covered with an abundant growth of timber.
We sometimes meet with ridges of coarse material, apparently drift
deposit, on which from some cause there has never been an
accumulation of fine sediment; in such localities we invariably find
a growth of timber. This is the origin of the groves scattered over
the prairies, for whose isolated position and peculiar circumstances
of growth we are unable to account in any other way."
Dr. Charles A. White, who made a later geological survey of Iowa,
in discussing this subject says:
"It is estimated that seven-eights
of the surface of Iowa was prairie when the State was first settled.
They are not confined to the level surface, but sometimes are quite
hilly and broken; and it has been shown that they are not confined
to any particular variety of soil, for they prevail equally upon
alluvial, drift and lacustral. Indeed we sometimes find a single
prairie whose surface includes all of these varieties, portions of
which may be sandy, gravelly, clayey, or loamy. Neither are they
confined to the regions of, nor does their character seem at all
dependent upon the formation which underlies them; for within the
State of Iowa they rest upon all formations from those of the Azoic
to those of the Cretaceous age inclusive, which embraces almost all
kinds of rocks. Southwestern Minnesota is almost one continuous
prairie upon the drift which rests directly upon not only the hard
Sioux quartzite, but also directly upon the granite.
"Thus whatever the origin of the
prairies might have been, we have positive assurance that their
present existence in Iowa and the immediate vicinity is not due to
the influence of the climate, the character or composition of the
soil, nor to the character of any of the underlying formations. The
cause of the present existence of prairies in Iowa is the presence
of autumnal fires. We have no evidence to show or to suggest that
any of the prairies ever had a growth of trees upon them. There
seems to be no good reason why we should regard the forests as any
more natural or normal condition of the surface than the prairies
are. Indeed it seems the more natural inference that the occupation
of the surface by the forests has taken place by dispersion from
original centers, and that they encroached upon the unoccupied
surface until they were met and checked by the destructive power of
fires. The prairies doubtless existed as such almost immediately
after the close of the Glacial epoch."
The International Cyclopedia, in an elaborate article on the
prairies, says:
"The origin of the very fertile
prairies of the valley of the Mississippi River proper has been the
subject of many theories. How a soil so rich upon which most of the
trees of neighboring forests flourish luxuriantly when protected
should have failed to have been covered with them in a state of
nature, is the question. It is answered by some vegetable
physiologists thus:
"The excerements of vegetable
growth from the roots of trees and plants, and even the annual
accumulation of their own leaves after a continuous growth of the
same species, become poisonous to the genera which emit them, though
perfectly nutritious to plants of different families. It is claimed
that the long continuance of forest growth on a rich soil made
constantly richer by its own annual deposits of leaves, dead wood
and excretions from the roots, finally makes it unfit for their
growth. Sickliness and decay produce more dead wood so that fires
finally destroy utterly what the soil refuses to nourish. Rank
weeds and grasses follow, which in their turn ripen and dry in
autumn, make food for new flames that destroy the remnant of tree
vegetation, and even the young wood of new species which might
otherwise hold their ground. Tree roots cannot live when their tops
are destroyed. Perennials, on the other hand, have an extraordinary
power to preserve life in their roots under the action of prairie
fires. Once in possession of the soil it is easy to see that annual
autumn fires, where there are not animals enough to feed down the
summer growth, will not only preserve the ground won from the forest
by grasses, but will singe the surrounding forests, and wherever
they are sickly from the cause first named will finally consume
them. Ages of the continuous growth of grasses and other perennials
have assimilated those qualities of the soil that become noxious to
trees; and in nature's rotation of crops, the soil has again become
fitted for their growth. It is only necessary to check the prairie
fires for a new crop of forest to dominate the grasses. Trees were
beginning to resume possession of the prairies when the settlements
began. The increase of the buffalo decreased the food for autumn
fires by so much as they pastured upon the grasses. The moisture of
the ground contiguous to streams, and the sweetness of the late
summer grasses in those places, would naturally make spots where the
trees could have time to get rooted in the absence of fires."
It will be seen from these quotations that the subject of the
origin of the prairies is by no means settled. Little, if anything
new, has been developed during the last quarter of a century by
scientific investigation to throw new light upon a subject that will
always be of interest in the Mississippi Valley. The fact that
prairie and forest conditions have been found on all of the
continents, and among the islands, when first seen by men, show
clearly that the solution of the problem cannot be found in local or
climatic conditions. Some of the treeless plains are the most
fertile lands known; some are level as the lakes; some are barren
deserts of drifting sands; others are lofty elevations rising into
hills and mountains; they exist in the Arctic regions, in the
temperate latitudes and in the torrid zones; some are entirely
destitute of sand, gravel or rocks of any description. Others are
thickly strewn with granite boulders, and in others arise enormous
ledges of rocks. In some places in Kansas the prairies are covered
with flat limestone, in sufficient quantities to fence the land into
fields with walls, as in New England and Pennsylvania with cobble
stones.
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