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| teacher guide
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Professional
Geologists Explore Iowa
page
7
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| The
mid-19th century was a time of exciting theories and discoveries
in science--including Darwin's On the Origin of Species,
and Mendel's studies on heredity. In geology, Europeans and
Americans were developing methods of relating time through rock
units.
When
the first investigations into Iowa's geologic history began
there were few roads or settlements. Early geologist found
swamps, thick forests, and endless prairie to challenge them.
Traveling on horseback and by canoe they based their work on the
rocks and fossils they observed and their studies of other
locations. Their reports became official documents of the state
and nation.
Nineteenth
century geologists faced many physical hardships as they entered
the new territory and state of Iowa.
"We
have frequently...exhausted the last pound of eatables, and
traveled a day or more without breaking our fast." We
lost, by death, but one man, of cholera, at Muscatine, in Iowa,
on July, 1849. Throughout the whole of that season, as cholera
was very prevalent...we had great difficulties in inducing
voyageurs to risk the exposure..." -- David D.
Owen
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David
Dale Owen: In
1839, before Iowa was a state, Owen left his studies in
the East and began to investigate the soils and mineral
resources of the upper Mississippi River valley at the
request of Congress. Here he found fossils and rocks that
were familiar to those of his boyhood in Scotland and his
earlier work in Indiana.
"The
coal-measures of Iowa are shallow much more so than those
of the Illinois coal field. They seem attenuated, as
towards the margin of an ancient carboniferous sea: not
averaging more than fifty fathoms in thickness."
--David D. Owen. |
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James
Hall:In
1855 the Iowa legislature appointed James Hall, former New York State
Geologist, to conduct a geological survey. He published the two volume
work in 1858.
"The
lower geological formations, therefore, of this great northwestern plateau
are the same as those known in New York and Pennsylvania, which form not
only the undisturbed portion of that part of the country, but also the
disturbed regions of the mountain ranges..." --James Hall |
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Charles
A. White: The legislature again attempted to
gather information about Iowa's mineral and agricultural wealth by
directing the new State Geologist, Charles A. White, to crate a new survey
and report in 1866. White's survey used the English system of rock unit
nomenclature, which recognized the sequence and allowed for individual
differences in rock units. Yet some of the earlier New York system names
that Hall encouraged remained. He extended his work by calculating the
thickness of Iowa rocks, above the Precambrian rocks, by relating the
position and thickness of known outcrops. |
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White's
geologic map of Iowa reflected new knowledge about the
relationship of one rock bed overlying or hiding another.
"All
such rocks have received their stratified form by having been
originally deposited as a precipitate or sediment in water, and
with rare exceptions they have been deposited in the waters of
the sea..."
-- Charles A. White |
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