- Today we are pleased to introduce Scott Spoolman
as part of the Wisconsin Historical Museum's
History Sandwiched In lecture series.
The opinions expressed today are those of the presenter
and are not necessarily those
of the Wisconsin Historical Society
or the museum's employees,
Scott Spoolman is a science writer
who has focused on the environmental sciences
especially those stories of natural science
and the environment related to Wisconsin
and surrounding states.
He grew up in northern Wisconsin
and after earning a master's degree
from the University of Minnesota School of Journalism
he worked for several years as an editor
in the publishing industry
specializing in textbooks and other educational materials.
Since 1996 he has worked as a freelance writer
for a variety of outlets and has co-authored several editions
of a series of environmental science textbooks.
So please join me today in welcoming Scott Spoolman.
(audience applauding)
- Good afternoon and welcome.
And thank you for coming here tonight, today,
it's great to see you, it's such a nice turnout.
And thanks to the Wisconsin Historical Museum
for hosting us.
We're here to talk about geology
and natural history of Wisconsin
as evidenced in our state parks.
And that reflects the title of my book
"Wisconsin State Parks: Extraordinary Stories
"of Geology and Natural History"
published by the Wisconsin Historical Society Press.
And I want to tell you how extraordinarily grateful I am to them
for taking an interest in this book idea
and I'm happy to have a few of them here today.
One other person I'd want to thank is my wife, Gail,
who's in the back there.
And she's given me good feedback and some ideas
that have been incorporated into the book.
She's also provided some nice snacks back there.
And she's also been a great coach,
she's coached me in these presentations.
And she's excellent, she's really good.
However, what that means is that
whatever happens here today you can blame on Gail.
I'll talk about the history
and the geology and the book a little bit
and then after that we can have some time for
questions and answers
and a book signing if you're interested.
Just one more thing before we get started.
I wanted to pay a tribute today
to a great teacher and writer who recently passed away,
Dr. Robert Dott co-authored
the "Roadside Geology of Wisconsin."
Among other great books including
the definitive historical geology textbook called
"Evolution of the Earth."
Those books were most helpful to me in this project
as was Bob himself who graciously answered
a lot of questions for me.
So here's to you Bob.
People often want to know why I wrote the book
and the main reason is that I've always been fascinated
by Wisconsin's various landscapes
and beautiful natural settings.
My parents got me going on this when I was young
by taking me to the places they enjoyed
such as this beautiful little place called Morgan Falls
up in the North Woods, up in Ashland County.
This was the beginning of my exploration
of the state's beautiful natural settings.
And since then, Gail and I have carried on the family tradition
taking our kids to the places we like to go to
including Devil's Lake State Park.
And we've all grown a bit since that picture was taken.
These experiences have also helped to shape my career
as an environmental science writer.
One of the things that caught my eye a few years ago
was this beautiful map produced by
the Wisconsin Geology and Natural History Survey.
It vividly shows Wisconsin's diverse
and distinctive landscapes.
And it occurred to me that the zoom in
on these areas and study them,
one could use Wisconsin's wonderful state parks
as entry points.
I think of the state parks as time portals
or gateways to the ancient past.
You walk through the gates of the park
and travel back in time.
And that idea fascinated me and I thought that by doing that
by exploring the parks and telling their stories in a book
I could share my fascination
with Wisconsin's geology and Natural History.
I would bet that many of you will agree
that what's also fascinating
is the enormity of the processes
that shaped these various landscapes...
such as the deep north, the deep woods of northern Wisconsin
and the cliffs on Door County on the east side of the state.
The Central Sand Plain with its buttes and spires
and sandstone mounds.
In the Driftless Area of Southwestern Wisconsin
with its deep valleys and river bluffs.
Understanding and appreciating these processes
involves some key geological concepts.
And one of those is the immense time scale
of the Earth's history.
I ask you to take yourselves out of our daily time frame
that we divide into hours and minutes and seconds
and smaller and smaller fractions of a second
and to put yourself into a much larger frame
that is measured in centuries and millennia
and millions and billions of years.
For our purposes today
there are four spans of time that I want to focus on.
First is the Precambrian age which is the first, excuse me,
the first four billion of the Earth's
4.6 billion-year history.
And it involved continental collisions
that built ancient North America.
And in the Wisconsin region it involved
volcanic activity and mountain building.
The next period is a period of
the invasions of the area by inland seas
starting with the Cambrian Period.
When life began to evolve in the first of those seas,
the earliest of those seas that invaded our area.
It was a 50 million-year span
during which at least a couple of ancient seas invaded
and then retreated from Wisconsin.
And it was followed by about 135 million years
of more invasions by inland seas
and more accelerating evolution
of the life that lived in those oceans.
During the next roughly 400 million years,
the last of the seas had departed
and Wisconsin was more or less high and dry.
Erosion took over as the main geologic force and
erased the record, the fossil record of all of that time.
So for example,
we don't know if dinosaurs roamed in Wisconsin
during the Jurassic.
I mean, we assume they did it, they probably did,
but we don't have any record of dinosaurs in our area,
thanks to erosion, it's all gone.
And finally the two and a half million year
Quaternary Period, the ice age,
becoming the glaciers.
And within the last 200,000 years the emergence of humans.
These periods are all explained much more fully in my book
in the introductory chapter
which tells the bigger geologic story of Wisconsin.
And gives an overview and introduces this
and other key concepts that help you
to fully appreciate the park stories.
Another such key idea was the fact that
for much of its history the Wisconsin region was tropical.
I want to thank the UW Press for the use of this image.
Author David Mickelson and his co-authors
used it in their fabulous book
the "Geology of the Ice Age National Scenic Trail"
which some of you have probably seen.
Early in its history the crust of the earth was fractured
into several large pieces called the tectonic plates.
And they were jostled and bumped around,
jostle and moved around on the mantle of the planet
which is the plastic hot rock that underlies
the crust of the Earth.
And the term plate tectonics refers
to this movement of the crustal plates
driven by the intense heat of the planet's interior.
The plate on Wisconsin road
was south of the equator in Precambrian time.
And it did kind of a curlicue path
as it moved around over time across the equator
which is right here.
(laughter)
Yes, it did.
About 350 million years ago
and continued on up to its current latitude
between 70 and 10 million years ago.
And we're still moving by the way.
Wisconsin is moving generally southwest now
and about the rate at which your fingernails are growing.
[laughter]
For this project, I divided the state
into five geographic regions.
Each park has its own story
and for each region I picked the five or six stories
that I thought best represented the dynamic processes
that occurred in the regions.
For example, in the northwest corner of the state.
Copper Falls State Park
was formed largely by a volcanic activity
and that's Brownstone Falls in that park.
And the rocks underlying
and all around that falls are volcanic.
In the northeast corner of the state,
the parks lie on the sediments of ancient sea creatures
that were converted into very hard rock
and then later unearthed by the glacier and other processes
creating features like these cliffs
that make Door County famous.
This one is in Peninsula State Park.
In the rolling countryside of southeastern Wisconsin,
glaciers formed the landscapes
such as this cone-shaped hill called a kame.
This one is Dundee Mountain
up at Kettle Moraine State Forest.
In the south-central region
several processes help to shape the land,
many of them related to the glacier.
For example, even during glacial times, during summer months,
water flowed into cracks and crevices of rock
and then during the very cold winters of that time
froze and expanded and widened the cracks and crevices
and eventually pried rock pieces apart.
And over the centuries this freeze thaw cycle
with its pickaxe effect literally sculpted rock features
such as the Balanced Rock at Devil's Lake State Park.
The same process created the talus slopes
of those piles of fractured quartzite
that are draped along the cliffs up there at Devil's Lake.
And finally in the southwest corner of the state
the Driftless Area where the glaciers never invaded,
the slow steady process of erosion formed features
such as Enee Point at Governor Dodge State Park.
This is a sandstone mass sculpted by wind and water erosion
over uninterrupted from hundreds of millions of years.
And that's my son Will in the photo there,
he was helping me that day.
All of these processes are explained more fully in my book.
I devoted a chapter to each of the regions
that I just reviewed.
Each chapter includes an introduction with more details
on regional geology and natural history,
followed by five or six park stories.
Each story that in turn has an introduction
that gives more details on the geology
and natural history of the park area.
And in many cases I also included some early human history
explaining how Native Americans lived in the park areas
and how they too viewed them as special and even sacred.
For example, the Trempealeau Mountain
up at Perrot State Park on the Mississippi River
north of La Crosse.
This has long been sacred ground to the Ho-Chunk
and access to it is restricted in honor of that.
Another area that is rich in Native American history
is the Driftless Area covered in chapter three of the book.
That chapter introduction includes
some material that archeologists have found
that tells the story of how people lived
in the distant past.
It's extraordinarily good archeological information.
And there are similar information
from the other regions of the state as well.
Now in the parks you will want to see the evidence
of the geologists and scientists and historians have used
to construct these park stories,
and you can do that by hiking the trails.
I've provided trail guides in my book
at least one for each park.
And these preview what you'll see
including rock types and formations
and how things have changed over time.
So right now let's go through one of those time portals
and we'll hike through one of the parks
going to Interstate Park.
It's the oldest of Wisconsin's parks,
a joint venture with the state of Minnesota
established in 1900.
What we'll see as we go
is a progression of extraordinary processes
including volcanic eruptions, invasions by ancient seas,
centuries of erosion, crushing glaciers
and finally a catastrophic flood.
The chapter in which this park is located is chapter two
and the following paragraph
from the introduction to that chapter sets the stage.
The northwest corner of Wisconsin
was shaped by unimaginable forces of extreme heat and cold.
Heat so intense that it melted rock deep in the Earth
forced it to the surface
and forged massive new layers of rock
thousands of feet thick over much of the area.
And cold so intense that it defied the sun,
captured and froze the Earth's water for centuries
and built a crushing deep field of ice
that spread over most of the state.
The interactions of these great masses of rock and ice
were largely what created the fascinating landscape
of northwestern Wisconsin.
Chapter two, the story of Interstate Park is in chapter two
and it's called the rift zone.
The chapter introduction explains that
a little over 1100 million years ago,
that's 1.1 billion years ago,
a massive plume of magma or hot liquid rock
rose up from deep in the Earth toward the crust
where it pried open this long crevasse
called the Midcontinent Rift.
It stretched from lower Michigan
all the way up through what would be the Lake Superior basin
and then southwest all the way down into
Nebraska and Kansas.
This rift could have split the continent in two
just as another earlier rift
split another earlier ancient continent
and created the Atlantic Ocean.
And you notice the long ridge
that lies along the center of that oceans floor,
that was built of lava that was spurting from that rift.
But something stopped the process in the Upper Midwest...
probably a continental collision to the southeast
that pushed everything back together again.
But this rifting process was responsible
for much of what we see there now in northwestern Wisconsin.
Over a period of 25 million years
lava spurted from the rift.
And in northwestern-most Wisconsin
the lava spread across a wide area
that included Interstate Park which is right about there.
Right in the middle of it all.
That lava would become basalt,
a dark-colored fine-grained very dense rock
that underlies northwestern-most Wisconsin.
Over those millions of years
multiple flows of this lava
built up to make a mass of basaltic rock
that was up to 20,000 feet
or nearly four miles thick in some areas.
The next major process
that affected the Interstate State Park area
was the coming of the Cambrian seas.
Now during the Cambrian
at least a couple of shallow seas invaded and retreated
in the Wisconsin region
and they might have resembled this mudflat area
on the east coast of the United States.
Now remember the area was,
the area that would become Wisconsin
was lying close to the equator
was something like a tropical desert,
there was no land vegetation.
So untold quantities of sand
were deposited by these shallow seas
accumulating for millions of years.
And eventually becoming layers of sandstone
totaling thousands of feet thick.
And this is an example of Cambrian sandstone.
After the Cambrian period came more inland seas
that deposited more sandstone
but life was evolving in these oceans
and becoming more diverse.
In Silurian time,
one of those periods that followed the Cambrian,
the seafloor might have looked something like this
right here in Wisconsin teeming with life.
This is a diorama on display in the Milwaukee Public Museum
and it's really worth a trip over there to see this
and all their other great geological exhibits.
Seafloor life included a variety of shelled animals
such as clinging brachiopods and crawling trilobites
and these tall, flower-like things here.
These are actually animals called crinoids or sea lilies
and the chief top predator in that system
was this long octopus looking like critter
called cephalopod.
The remains of these creatures collected on the sea floors
for many millions of years
and eventually became limestone
which by chemical reactions
was converted to something called dolomite.
A harder rock more resistant to erosion
and often rich in fossils.
Now all of Wisconsin was once covered by dolomite
and much of it has been eroded away
during that long period of erosion,
exposing the older, deeper sandstone in some areas
including the Interstate Park area.
Eventually forests covered the land
and the area around Interstate Park
was a rolling forested plain lying on land stone,
just lying on sandstone, just before the glaciers came.
This is actually a picture of the Wisconsin River Valley,
I took that photo in Wyalusing State Park.
But before the climate cooled and the glaciers arrived
the ancient St. Croix River Valley
might have looked something like that.
Well then came the glaciers.
There were several glaciers during the roughly
two and a half million-year Ice Age.
Some of you all just think as many as 15 major ice sheets
flowed down from Canada.
But the most recent one is called the Wisconsin Glaciation
because Wisconsin contains
some of the best examples in the world
of what a glacier can do to the land,
how it can change the landscape.
This glacier entered Wisconsin about 30,000 years ago.
And at its peak the ice sheet over Interstate Park
was well over 1,000 feet thick,
so that's roughly the height of the Empire State Building.
And it might have looked something like this glacier
in Greenland.
Eventually the climate warmed again
and the glaciers began to melt.
It retreated in fits and starts
and finally melted out
of the northernmost part of Wisconsin
between 11,000 and 10,000 years ago.
An interesting side note, if you did the math,
you realized that that glacier just the most recent one,
the Wisconsin glaciation
was in the state for 20,000 years.
That's about four times as long as the
all recorded human history,
so it gives you some perspective.
Now when glaciers melt away
the melt waters form lakes called
glacial lakes in low-lying areas.
And big glacial lakes can form against
the retreating ice wall and sit for centuries,
thousands of years in fact.
One such lake was Glacial Lake Duluth
which occupied various portions
of the Lake Superior basin for centuries.
At its southern end was a dam made mostly of ice
with some rocks and sand and gravel from the glaciers,
and it was located about 80 to 100 miles north-northeast
of the Interstate Park area which is right here.
With the climate warming and the ice melting
that dams days were numbered.
And when the rising glacial lake waters
finally overwhelmed the dam,
the resulting flood was a catastrophic force of nature.
Icy melt waters roared down this valley
of the ancient St. Croix River.
When the flood from the glacial lake
arrived at the park area
it probably engulfed all of is now Interstate Park.
It tore away much of the softer sandstone
and then went to work on the underlying basalt bedrock,
the harder rock.
Began chiseling at this basalt
by working at its vertical cracks.
And chunks of the basalt would come loose
and be tumbled down the riverbed by the massive flood.
And as the channel became deeper
the water acquired more force
and this chiseling digging effect became stronger
and the carving quickened.
In this way the icy blast of water
dug a deep narrow gorge piece by piece.
It probably took a few hundred years,
which in geologic time is quick.
And this was the result.
And this is what I mean by going back in time.
This little canyon at Interstate park called
the Dells of the St. Croix
was carved by that post-glacial flood
that I just mentioned, described.
And you can get this stunning view
by hiking on a trail called the Potholes Trail.
And on that trail of course
you can also see some of Interstate Parks famous potholes.
And this one is about five feet across
and goes down about eight or nine feet.
It was formed by gravel and rocks
that got stuck an eddy of the massive flood
and there were whirling ferociously against
the bedrock for decades or centuries
until this hole was literally drilled into the bedrock.
There are many other potholes in the park
and some of them are much bigger than, than this one.
At this point on the Potholes Trail
you are about 100 feet above the river.
And this is how we know that the post-glacial flood
must have spread across the entire park for centuries,
drilling holes here and there
while it was excavating that gorge.
When glacial Lake Duluth finally drained to a certain level,
the river level also dropped
leaving the potholes high over the river where they are now.
Now a little south of the potholes on another trail
called the Skyline Trail,
you can visualize the great flood filling the valley.
These little tick marks here
represent the southeast rim of the valley,
the ancient St. Croix River Valley
or actually the current St. Croix River Valley.
And this, the other, the northwest rim of the valley
is along this highway in Minnesota.
And Skyline Trail skirts the southeast rim of the valley.
The Skyline Trail guide includes the following:
"As you hike on the trail along the rim of the River Valley,
"imagine the great flood of ice water that rolled through
"filling the valley almost to the brim
"as the glacier retreated 10,000 years ago."
"The surrounding land would have been tundra, no forests,
"hosting only extreme cold weather species
"such as lichens, some grasses, stunted alder
"and spruce trees, musk oxen and caribou."
And it might have looked something like this...
current day meltwater flood going on in Iceland.
From still another trail called the River Bluff Trail
you can look across the St. Croix River
for a good view of one of the walls of the gorge
and the mass of basalt that was laid down
over that 25- million-year period.
This is just the top...
Where's my pointer? There it is.
This is just the top 100 feet or so of a mass of basalt
that's probably thousands of feet thick at this point.
And you can also see how the basalt
was fractured into blocks
by these vertical and horizontal cracks.
Do you see the rock climbers in this photo?
There's one right in the middle going straight up,
there's one over here making an angular move.
Notice those people are working their way up this rock face
using those crack and crevices,
some of which were formed
long before humans even existed on the planet.
Let alone before some humans decided
it was a good idea to go climb rock walls.
[laughter]
Rock climbers love this kind of rock.
So we've come to the end of our hike
through Interstate Park.
This is one of several pine groves
that you can visit in the park.
After the last glacier retreated,
great pine forests became established over most of Wisconsin
and stood for thousands of years as I'm sure you know.
Since they were logged in the early 20th century,
the forest in the park area has reclaimed the land
and some nice stands of red and white pine like this
can give you a sense of the ancient forest.
I'll leave you with the following paragraph
which reflects one of my most memorable experiences
hiking in the parks.
And this is from the Interstate Park story.
What covers much of Interstate Park now
is 2nd and 3rd growth forests
that have their own remarkable beauty
if not the majesty of the ancient pine forest.
Nevertheless when you are hiking
on one of the many trails in the park
that passed through small groves of red or white pine,
stop for a moment and close your eyes.
Smell the scented air
and listen for the delicate song of the wind in the pines.
You might then imagine yourself
to be in that vast deep forest that once stood here
the top gravel and soil dropped by the glacier...
on top of sandstone and limestone deposited by ancient seas.
On top of bedrock laid down a billion years ago.
Thank you.
(audience applauding)