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[gentle music]

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- Nancy Larson: Thanks for
coming, everybody, tonight.

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So, tonight we have the pleasure

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of hosting a Badger Talk
this evening.

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The University of Wisconsin's

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Badger Talk program
carries on a tradition

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of the Wisconsin Idea

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by bringing University's
research and expertise

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to communities across Wisconsin.

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Through this free program,
more than 600 faculty and staff

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connect with schools
and libraries

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and community organizations
to share knowledge

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and discuss topics that matter
to the people of our state.

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Tonight, we have the pleasure
of welcoming Sue Swanson,

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the state geologist and director

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of the Wisconsin Geological
and Natural History Survey.

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Sue leads statewide efforts

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to advance the understanding
and use

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of Wisconsin's
geological resources.

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So, this evening,
she will provide

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an overview
of the geology of Wisconsin.

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So, welcome, Sue.

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[audience applauds]

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- Sue Swanson:
It's a pleasure being here.

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Thank you for coming out tonight
to learn a little bit

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about the geology of Wisconsin,

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and also to learn
a little bit about the work

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of the Wisconsin Geological
and Natural History Survey,

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which we call "the Survey."

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So, if I start talking
about the Survey,

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I'm talking about the work

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of the Wisconsin
Geological Survey.

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So, as Nancy said,

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the Survey is part of UW-Madison
Division of Extension,

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and I'm the director and
I'm also your state geologist.

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Okay, so we're gonna jump
right in.

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And usually, when we start
talking about geology,

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people start
thinking about rocks.

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And that's great,
think about rocks.

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There are rocks in these
images that you're looking at.

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But when a geologist looks at
a suite of images like this,

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we also think about
the geologic processes

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that formed the landscapes
and outcrops

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that you're looking at.

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And we think about
the long Earth history

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that led to our landscape
that we have today.

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And the rocks
that are visible at the surface.

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And so, you know, geologists
actually, you know,

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we really enjoy studying rocks,

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but those processes are often
where we specialize.

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And when I say processes,

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I mean things like
glacial activity, right?

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Volcanism, right?

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Stream erosion.

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So, all of the things

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that ultimately form
geologic materials,

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help to erode and transport
geologic materials.

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I'm actually a hydrogeologist.

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So, I study groundwater flow.

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And all geologists use
our knowledge

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of rocks and Earth history.

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We combine other sciences,
like physics and chemistry,

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to better understand some
of the processes

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that we're most interested in.

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And for me, like I said,
it's groundwater flow,

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but I'm gonna--
I'm gonna cover all sorts

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of different processes
and rock types

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and a lot of Earth history
tonight.

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Okay?

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Okay, so, I'll also mention
some of the landscapes

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that you're looking at

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as we go through
the talk tonight.

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So, you might recognize
some of these places.

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In the upper right-hand corner,

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we're looking at the
Wisconsin River.

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In the lower right-hand corner
and in the middle,

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there are some outcrops
from the Baraboo area

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and Devil's Lake State Park.

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In the upper left-hand corner,

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that's a rock exposure
or outcrop just southwest

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of Platteville, Wisconsin,
in southwestern Wisconsin.

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And then, the lower
left-hand corner,

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that's up on the Lake Superior
coast in Bayfield County,

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the sea caves, if any of you
have ever been there.

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All right, and here's what
we're gonna tackle tonight.

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We'll start out by thinking
about contributions of geology

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to the state's livelihood.

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Why should we care
about geology, right?

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I have to kind of back up
really far back, you'll see,

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to include a discussion
about geologic time.

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Geologists need to describe
an immense period of time.

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And we need language and
classification schemes to do so.

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So, we'll talk about
geologic time.

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Then we'll be able to talk about
the geologic history

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of what we call Wisconsin today.

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And then, finally,
I'll kind of wrap up

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with some of the current efforts

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that we have ongoing
at the State Geological Survey.

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Okay, contributions
to the state's livelihood.

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If I were to think about
sort of three

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of the biggest
economic endeavors

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in the state of Wisconsin,

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hopefully tourism would come
to mind,

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agriculture, and industry.

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Okay, so if we start out
with tourism,

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I'm gonna show a series
of images

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from state parks in Wisconsin.

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And maybe you've been to some of
these locations and, you know,

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not every single state park,

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but a lot of state parks are set
aside for, at least in part,

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right, for the unique geology

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or special landscapes
within their boundaries, okay?

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So, Peninsula State Park,

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up in the northeastern part
of the state, in Door County,

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Wyalusing in the southwestern
part of the state,

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near the Mississippi River.

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Devil's Lake, I mentioned.

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Rib Mountain up near Wausau,
okay?

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Let's see, Governor Dodge,
just west of Madison,

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Copper Falls up
in Ashland County.

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And then, Willow River,

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just outside of Hudson,
Wisconsin, okay?

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All right,
then agriculture, right?

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So, on the right-hand side
of the slide,

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what you can see is a map
of soil regions in Wisconsin.

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And we know we have world-class
agricultural soils in Wisconsin.

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And that is in large part

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due to the underlying
geologic materials.

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Rocks, right?

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But also these processes
that shaped the landscape

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and eroded materials,

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transported it,
and deposited it in Wisconsin.

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And then, of course,
soils are a combination of that,

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that geologic material
with biological material,

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and then also taking into
account the climate of a region.

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But the geology is
really important

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in understanding
the distribution of soils

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and really plays into the fact
that we have--

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we have fantastic agricultural
soils in the state.

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There's a picture up
in the upper left-hand corner

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that shows an agricultural
landscape, right?

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What I really like
about this image is if you--

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if you've ever studied
a topographic map,

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then topographic contour lines,
they represent elevation.

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And when you see them
kind of looping around kind of

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in a bull's-eye pattern, you
know you're looking at a hill.

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Okay?

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And so, what's really neat
about this image

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is that the pattern of the
fields are mimicking

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topographic or elevational
contour lines.

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And I, when I look at it,
I can see, oh, well, there's,

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there's a streamlined hill

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that is also the result of
glacial activity in that region.

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We have abundant water resources
in the state too.

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And, of course, that plays
into the agricultural economy.

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And so, also as a result
of glacial activity,

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much of Wisconsin
had vast wetlands, right?

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Low-lying areas in between some
of the hills

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that are depicted in that
upper left-hand slide,

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right, or picture.

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And so, some
of those wetland areas

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are used as cranberry bogs
today, right?

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And then, up in the upper
right-hand corner of the images,

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there's a picture
of a milk house

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or a spring house
on a farm in southern Wisconsin.

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And I like to show this one

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because it touches
on a couple of things, right?

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So, there's a natural spring
discharging

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into that milk house
or spring house, right?

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And so, these types
of structures

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were really important.

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You know, even today, right,

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in keeping food stocks nice
and cool in the summer

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because of the discharging
groundwater

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or keeping food from freezing,
right, in the winter.

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Because groundwater has
a pretty consistent temperature

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all year long.

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Okay, groundwater
doesn't freeze, right?

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And in Wisconsin, it's roughly
the temperature

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that is equivalent to the
mean annual air temperature,

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which is
about 10 degrees Celsius

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or 50 degrees Fahrenheit.

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So, it's great for that purpose.

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Discharging groundwater
like that also feeds not only

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this little pond
that this particular farmer

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has stocked with trout,
it also feeds trout streams,

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natural trout streams
throughout the state,

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which we know, you know, brings
in, you know, lots of tourism,

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but then we have,
you know,

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an active aquaculture industry
in the state.

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Okay, and then, in terms
of industry, okay.

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Mining is closely tied
to geological resources,

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and the way
that we typically think about

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these geologic materials that
are mined and extracted

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from the Earth
are to think about them

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as nonmetallic resources
and metallic resources, okay?

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So, for the
nonmetallic resources,

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we have aggregate or sand
and gravel,

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crushed stone that we use
in construction, right?

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You've all seen
gravel pits across the state.

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Sand is mined from some
of the sandstone layers

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that I'll talk about later,
and that's used in foundries,

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in the glass industry.

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It's also used in the oil
industry as frac sands, right?

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So, we don't have any
petroleum sources really

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in Wisconsin,
we don't have oil wells,

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but the sand that is mined

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gets used as frac sand
in the oil industry, okay?

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Dimension stone
for monuments, right?

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We have-- You'll see in our past
a volcanic history, okay?

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And one volcanic rock type
is called andesite.

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And it's mined and crushed
and is used

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as the little pieces
on roofing shingles, okay?

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And then, of course,
peat, right,

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is used in horticultural
and landscaping industry.

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So, a variety
of nonmetallic mining.

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And then, of course,
metallic mining.

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So, similarly, we're gonna break
metallic mining up,

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okay, into containing iron,
or ferrous resources,

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or other metals,
nonferrous, okay?

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In the middle
of this slide,

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I have a picture of what's
called banded iron formation.

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And this is the rock type
that really formed the basis

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for a lot of the iron mining in
the Upper Peninsula of Michigan,

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northern Wisconsin,
Minnesota.

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We'll talk a little bit about
when and how that was--

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that was formed
in that region.

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We also--
I mentioned already

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that we had some
volcanic activity in our past,

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and that led to the formation
of other types of minerals

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that contain metals like copper,
gold, nickel, silver, right?

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So, we have nonferrous
metallic mining in Wisconsin,

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too, or at least we have
in the past.

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It's primarily these sites

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that are getting
some attention these days.

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And there's a few sites,
one in particular,

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that is being actively explored
in northern Wisconsin today.

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I also have on the slide,
in southwestern Wisconsin,

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pointing to this
historic lead and zinc district.

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Okay, and this was a really
important district in the 1800s,

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actually, all the way up
to the 1970s.

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It was one of the largest lead
mining districts in the 1800s.

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Later, zinc was mined.

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And like I said,

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that continued
up into the 1970s.

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Also with respect to industry,

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we can't forget about water,
right?

248
00:13:21,969 --> 00:13:27,908
And so, Wisconsin actually has
a number of spring resources.

249
00:13:27,975 --> 00:13:29,943
Natural springs, okay?

250
00:13:30,010 --> 00:13:33,180
And again,
it's sort of in the late 1800s,

251
00:13:33,247 --> 00:13:36,350
Waukesha, Wisconsin was
actually known as Spring City.

252
00:13:36,416 --> 00:13:40,354
And wealthy folks
from Chicago would come up

253
00:13:40,420 --> 00:13:42,523
and sit next
to beautiful gazebos

254
00:13:42,589 --> 00:13:46,360
that were built
around springs and vacation.

255
00:13:46,426 --> 00:13:49,162
Even then,
spring water was bottled.

256
00:13:49,229 --> 00:13:51,865
So, you can see
in the image there, Bethesda,

257
00:13:51,932 --> 00:13:54,601
the water of quality, right?

258
00:13:55,235 --> 00:14:00,340
And spring water is bottled
today still in Wisconsin.

259
00:14:00,407 --> 00:14:03,911
Our abundant groundwater
resources have also contributed

260
00:14:03,977 --> 00:14:06,547
to the success
of some other canned

261
00:14:06,613 --> 00:14:09,850
or bottled beverages
in the state.

262
00:14:11,585 --> 00:14:14,288
Okay, so, what is geology,
all right?

263
00:14:14,354 --> 00:14:15,656
And then, what we'll do

264
00:14:15,722 --> 00:14:19,426
is we'll kind of get into
geologic time, like I said,

265
00:14:19,493 --> 00:14:23,363
and then the history within the
state of Wisconsin, okay?

266
00:14:23,430 --> 00:14:24,898
So, what is geology?

267
00:14:24,965 --> 00:14:28,068
Broadly, it's the study
of solid earth, right?

268
00:14:28,135 --> 00:14:29,503
And when I say "earth,"

269
00:14:29,570 --> 00:14:32,439
I mean both the materials
that make up the planet

270
00:14:32,506 --> 00:14:36,210
and those processes
that I referred to before,

271
00:14:36,276 --> 00:14:39,413
whether volcanic
or whether seismic,

272
00:14:39,479 --> 00:14:43,183
earthquake, right,
glacial, stream, wind, coastal,

273
00:14:43,250 --> 00:14:44,985
all sorts of great processes,

274
00:14:45,052 --> 00:14:48,755
right, that end up shaping
the earth.

275
00:14:48,822 --> 00:14:51,758
There's two main branches
of geology,

276
00:14:51,825 --> 00:14:54,494
physical geology
and historical geology.

277
00:14:54,561 --> 00:14:57,097
I'm gonna be talking
mostly about physical geology.

278
00:14:57,164 --> 00:14:59,600
Really is-- That's really
much more focused

279
00:14:59,666 --> 00:15:03,370
on those processes
that I've mentioned.

280
00:15:03,437 --> 00:15:07,241
Historical geology gets more
into the evolution

281
00:15:07,307 --> 00:15:10,978
of the continents and life forms
through geologic time.

282
00:15:11,044 --> 00:15:13,647
The State Geological Survey,
we, you know,

283
00:15:13,714 --> 00:15:19,453
we think about the evolution
of the lithospheric plates

284
00:15:19,520 --> 00:15:23,457
that make up the upper layer
of the Earth.

285
00:15:23,524 --> 00:15:26,660
But we don't--
We kind of rely on it

286
00:15:27,394 --> 00:15:29,530
in order to have
a better understanding

287
00:15:29,596 --> 00:15:32,266
of a broad landscape, okay?

288
00:15:32,332 --> 00:15:36,003
And we don't do a lot
of paleontology.

289
00:15:36,069 --> 00:15:38,071
We use our knowledge of fossils

290
00:15:38,138 --> 00:15:41,675
to better understand
the age of different rock types.

291
00:15:41,742 --> 00:15:44,478
But we tend
to do less historical geology

292
00:15:44,545 --> 00:15:47,548
at the State Geological Survey.

293
00:15:48,782 --> 00:15:51,351
All right, deep time, okay?

294
00:15:51,418 --> 00:15:53,353
So, here I'm actually
gonna ask you

295
00:15:53,420 --> 00:15:55,522
to participate a little bit.

296
00:15:55,589 --> 00:16:00,227
And so, deep time is
a concept in the geosciences

297
00:16:00,294 --> 00:16:04,531
that tries to capture
the vast expanse of time

298
00:16:05,199 --> 00:16:08,569
that we have to try
to wrap our head around

299
00:16:08,635 --> 00:16:13,106
when we are thinking about
geologic processes.

300
00:16:13,807 --> 00:16:16,844
And so, I like
to always show an image

301
00:16:16,910 --> 00:16:18,745
of the Grand Canyon.

302
00:16:18,812 --> 00:16:20,047
I took this picture.

303
00:16:20,113 --> 00:16:24,384
And for me, when I stand
in the rim of the Grand Canyon,

304
00:16:24,451 --> 00:16:27,354
it's--
I'm sort of speechless.

305
00:16:27,754 --> 00:16:29,456
Right?

306
00:16:29,523 --> 00:16:31,959
The age of the materials
is vast,

307
00:16:32,025 --> 00:16:35,195
from the base of the canyon
up to the rim.

308
00:16:35,262 --> 00:16:38,432
And then, the canyon was formed.

309
00:16:38,498 --> 00:16:40,200
All of this erosion,

310
00:16:40,267 --> 00:16:43,637
right, to actually form what we
see as the Grand Canyon today.

311
00:16:43,704 --> 00:16:46,573
That took so much time, right?

312
00:16:46,640 --> 00:16:49,977
Geologists call it deep time,
okay?

313
00:16:51,111 --> 00:16:54,715
And so,
here's the exercise, right?

314
00:16:54,781 --> 00:16:58,285
So, if I said, do you kind of
have a gut feeling

315
00:16:58,352 --> 00:17:00,254
for one year of time,

316
00:17:01,421 --> 00:17:05,492
like I can kind of reason
through how long a year is?

317
00:17:05,559 --> 00:17:07,227
Yeah, sure, okay.

318
00:17:07,561 --> 00:17:09,363
How about 10 years?

319
00:17:09,730 --> 00:17:13,133
Like, I-- Like, myself,
I get a decade.

320
00:17:13,200 --> 00:17:14,868
Yep.

321
00:17:15,369 --> 00:17:17,037
Fifty years?

322
00:17:17,304 --> 00:17:21,141
Okay, I can wrap my head
around that, right?

323
00:17:21,208 --> 00:17:23,844
Seeing a couple fewer hands,
but some people are shy.

324
00:17:23,911 --> 00:17:25,879
You don't have to raise
your hands, right?

325
00:17:25,946 --> 00:17:27,881
Let's really jump, right?

326
00:17:27,948 --> 00:17:29,950
Let's go to 500 years.

327
00:17:30,951 --> 00:17:33,187
Okay, I can do the math, right?

328
00:17:33,253 --> 00:17:36,323
And I can reason
how that compares to 50.

329
00:17:36,390 --> 00:17:38,458
But do I really get 500?

330
00:17:38,525 --> 00:17:41,094
It gets pretty fuzzy for me.

331
00:17:41,929 --> 00:17:43,764
Fifty thousand?

332
00:17:43,830 --> 00:17:45,499
Five million?

333
00:17:45,933 --> 00:17:48,335
How about 3 billion?
[audience chuckles]

334
00:17:48,402 --> 00:17:53,040
Right, it's really hard
to wrap our heads around, okay?

335
00:17:53,106 --> 00:17:57,344
And so, what geologists do
is sometimes we use

336
00:17:58,212 --> 00:18:02,683
sort of analogies to try
and describe all of that time.

337
00:18:02,749 --> 00:18:06,153
And this is one
that is very well known.

338
00:18:06,220 --> 00:18:11,658
And it's from a popular intro
to geology textbook, right?

339
00:18:11,725 --> 00:18:13,160
This spiral.

340
00:18:13,227 --> 00:18:17,397
And if we look way down
at the beginning of that spiral,

341
00:18:17,464 --> 00:18:20,000
what that's supposed
to be representing

342
00:18:20,067 --> 00:18:23,670
is when the Solar System
and Earth formed,

343
00:18:23,737 --> 00:18:27,508
right, maybe
over 4 billion years ago,

344
00:18:27,574 --> 00:18:30,377
the gas and dust
came together

345
00:18:31,078 --> 00:18:34,515
and formed our
planetary body, right?

346
00:18:34,581 --> 00:18:39,586
But even then, it was
very different than Earth today.

347
00:18:39,653 --> 00:18:42,322
Different layers
needed to differentiate

348
00:18:42,389 --> 00:18:46,727
into what we know today
as the core, the mantle,

349
00:18:47,261 --> 00:18:48,829
and the crust of the Earth.

350
00:18:48,896 --> 00:18:51,999
If you've heard of
those layers, right?

351
00:18:52,065 --> 00:18:57,371
Life on Earth may have started
over 3 billion years ago.

352
00:18:57,437 --> 00:19:02,042
But things that we might
recognize more readily as life,

353
00:19:02,109 --> 00:19:05,345
you know, much, much later,
right?

354
00:19:06,046 --> 00:19:07,981
What's really,
really important is

355
00:19:08,048 --> 00:19:10,717
how incomplete our history is.

356
00:19:10,784 --> 00:19:13,854
And so, you know,
think about a novel.

357
00:19:13,921 --> 00:19:17,758
We're surrounded by books here
in this library, right? [laughs]

358
00:19:17,824 --> 00:19:21,828
Think about a book,
a novel, 350 pages long.

359
00:19:22,596 --> 00:19:26,733
What geologists
might have is page 26, okay?

360
00:19:29,136 --> 00:19:32,272
And then,
one sentence on page 74,

361
00:19:35,042 --> 00:19:39,613
and then a paragraph on page 75,
and then a page...

362
00:19:44,418 --> 00:19:46,954
Pick a number,
I don't know, 150, right?

363
00:19:47,020 --> 00:19:48,288
You get the pattern.

364
00:19:48,355 --> 00:19:50,023
Very incomplete.

365
00:19:50,290 --> 00:19:52,826
We tend to have more information

366
00:19:52,893 --> 00:19:56,063
the closer we are
to the present, right?

367
00:19:56,129 --> 00:19:58,999
And so, that also helps
kind of explain this spiral.

368
00:19:59,066 --> 00:20:03,070
It's a lot more detailed
near the end, okay?

369
00:20:03,604 --> 00:20:07,074
And another really
important thing is that,

370
00:20:07,140 --> 00:20:09,743
that over the course
of Earth history,

371
00:20:09,810 --> 00:20:14,348
some processes happened
very slowly, progressively.

372
00:20:14,414 --> 00:20:19,753
But there were other things
that were catastrophic, right?

373
00:20:19,820 --> 00:20:23,390
And had a big impact
over a short period of time.

374
00:20:23,457 --> 00:20:25,759
Both of those types of processes

375
00:20:25,826 --> 00:20:29,830
are very important
in Earth history, okay?

376
00:20:30,664 --> 00:20:33,233
In terms of the time periods

377
00:20:33,934 --> 00:20:36,103
that we're gonna be
talking about,

378
00:20:36,170 --> 00:20:39,206
if you can see
where it says Paleozoic Era,

379
00:20:39,273 --> 00:20:42,943
right on the top of--
on the top layer of that spiral,

380
00:20:43,010 --> 00:20:47,114
that's where we're gonna spend
really most of our time today.

381
00:20:47,181 --> 00:20:52,953
But most of it-- most of Earth
history is before that, okay?

382
00:20:53,020 --> 00:20:55,756
So, how else do
we organize all of this time?

383
00:20:55,822 --> 00:20:58,992
We use a geologic
time scale in geology, okay?

384
00:20:59,059 --> 00:21:01,061
And so, just like I said,

385
00:21:01,128 --> 00:21:05,866
those bottom three
gray rows labeled Precambrian,

386
00:21:05,933 --> 00:21:08,602
that's most of Earth history,
okay?

387
00:21:08,669 --> 00:21:10,604
We are gonna get into that
middle one,

388
00:21:10,671 --> 00:21:13,574
the Archean and Proterozoic
a little bit.

389
00:21:13,640 --> 00:21:15,676
And then, we're gonna spend
most of our time

390
00:21:15,742 --> 00:21:17,611
in the Phanerozoic, right?

391
00:21:17,678 --> 00:21:20,747
The Paleozoic, Mesozoic,
and Cenozoic.

392
00:21:20,814 --> 00:21:26,520
The bars that are hanging down
are labeled with life forms

393
00:21:26,587 --> 00:21:28,889
that we think evolved
around that time,

394
00:21:28,956 --> 00:21:31,758
and whether they're
still around today.

395
00:21:31,825 --> 00:21:33,660
Okay?

396
00:21:33,727 --> 00:21:34,995
All right.

397
00:21:35,062 --> 00:21:40,167
So, let's jump in to Wisconsin's
geologic history, okay?

398
00:21:40,234 --> 00:21:43,170
And so, here's a poster
that you can download

399
00:21:43,237 --> 00:21:45,906
from the State Geological Survey
website.

400
00:21:45,973 --> 00:21:51,411
And we'll start with the image
on the right-hand side.

401
00:21:51,478 --> 00:21:53,614
And so, in Milwaukee,

402
00:21:53,680 --> 00:21:57,084
actually, that's a location
in the state

403
00:21:57,150 --> 00:22:00,621
that if you wanted
to create a section

404
00:22:02,289 --> 00:22:04,258
or drill a really deep well

405
00:22:04,324 --> 00:22:08,562
that encompasses
pretty much every rock type

406
00:22:10,597 --> 00:22:13,967
in Wisconsin, that's a really
good place to do it, right?

407
00:22:14,034 --> 00:22:18,639
So, the oldest rocks are
at the base, the Precambrian.

408
00:22:18,705 --> 00:22:22,176
Then we get into
Paleozoic rocks, right?

409
00:22:22,242 --> 00:22:26,847
Cambrian, Ordovician,
Silurian, Devonian.

410
00:22:26,914 --> 00:22:28,215
Okay?

411
00:22:28,282 --> 00:22:33,187
Then there's a huge gap
in geologic materials, okay?

412
00:22:34,521 --> 00:22:36,924
Between those
Devonian Age materials

413
00:22:36,990 --> 00:22:38,725
and the Quaternary materials,

414
00:22:38,792 --> 00:22:41,695
the, largely
the glacial materials, right?

415
00:22:41,762 --> 00:22:44,765
Looser sediment
rather than rock, okay?

416
00:22:44,831 --> 00:22:48,702
And we'll kind of dig in
to what I mean by all of that.

417
00:22:48,769 --> 00:22:51,839
But first,
let's look over at the map too.

418
00:22:51,905 --> 00:22:53,507
And on the next slide,

419
00:22:53,574 --> 00:22:55,008
we're only gonna look
at the map

420
00:22:55,075 --> 00:22:58,979
and then that
cross section at the bottom.

421
00:22:59,479 --> 00:23:02,416
It's really helpful
to think about a cross section

422
00:23:02,482 --> 00:23:04,685
across the state
to understand what's going on

423
00:23:04,751 --> 00:23:07,988
with the patterns in the map,
okay?

424
00:23:08,455 --> 00:23:11,458
And so, if I drew a line
from western Wisconsin

425
00:23:11,525 --> 00:23:13,694
over to the Milwaukee area,

426
00:23:13,760 --> 00:23:18,899
and then I took a slice out
of the Earth along that line.

427
00:23:18,966 --> 00:23:22,703
You know, think of a layer cake
and slicing down vertically.

428
00:23:22,769 --> 00:23:24,538
You see the layers
in the layer cake.

429
00:23:24,605 --> 00:23:26,607
That's kind of what
the cross section is doing

430
00:23:26,673 --> 00:23:29,510
along that cross section line,
okay?

431
00:23:29,576 --> 00:23:32,012
And so, at the base
are the oldest rocks,

432
00:23:32,079 --> 00:23:35,249
the Precambrian rocks,
and then the Cambrian,

433
00:23:35,315 --> 00:23:36,917
Ordovician, Silurian,

434
00:23:36,984 --> 00:23:40,020
and a little bit of Devonian
there over by Milwaukee.

435
00:23:40,087 --> 00:23:41,955
And then,
there's sort of a drape

436
00:23:42,022 --> 00:23:45,792
of the Quaternary sediments
up on top.

437
00:23:45,859 --> 00:23:47,528
But at this scale,
you don't even--

438
00:23:47,594 --> 00:23:50,831
you really don't even see 'em,
okay?

439
00:23:50,898 --> 00:23:53,867
The other thing
to note is, on the eastern side

440
00:23:53,934 --> 00:23:55,736
of that cross section,

441
00:23:55,802 --> 00:23:59,473
the rock layers are dipping
ever so slow--

442
00:23:59,540 --> 00:24:03,544
not slowly,
slightly off to the east, okay?

443
00:24:05,345 --> 00:24:08,215
They're mostly horizontal
through the central part

444
00:24:08,282 --> 00:24:09,950
of the cross section.

445
00:24:10,017 --> 00:24:13,921
In western Wisconsin,
those rock layers are sloping

446
00:24:13,987 --> 00:24:18,192
or dipping ever so slightly off
to the west.

447
00:24:18,258 --> 00:24:22,663
In southern Wisconsin,
those rock layers are dipping

448
00:24:22,729 --> 00:24:27,401
or sloping ever so slightly off
to the south, okay?

449
00:24:28,602 --> 00:24:32,873
And so, ultimately,
that pattern of rocks

450
00:24:32,940 --> 00:24:37,611
has to do with that sloping
of these layers, right?

451
00:24:38,879 --> 00:24:42,382
And so, if you--
I'm surrounded by books, right?

452
00:24:42,449 --> 00:24:44,418
But if I had a book here, right,

453
00:24:44,484 --> 00:24:48,055
and I rotated it
a little bit and bent it,

454
00:24:48,121 --> 00:24:50,591
which they probably
wouldn't like,

455
00:24:50,657 --> 00:24:52,426
then part of the book

456
00:24:52,492 --> 00:24:56,063
would be sloping ever
so slightly in one direction,

457
00:24:56,129 --> 00:24:58,031
ever so slightly
in the other direction,

458
00:24:58,098 --> 00:25:00,267
ever so slightly towards you.

459
00:25:00,334 --> 00:25:04,338
And I-- I'd see the pages
on the side, right?

460
00:25:05,172 --> 00:25:08,242
And that's kind of
what we see in Wisconsin, right?

461
00:25:08,308 --> 00:25:10,244
Sort of that happy face pattern.

462
00:25:10,310 --> 00:25:11,879
Those rocks are tilted,

463
00:25:11,945 --> 00:25:13,847
so we're seeing the edges
of them

464
00:25:13,914 --> 00:25:16,950
as those layers have
been eroded off.

465
00:25:17,017 --> 00:25:21,355
Okay, so those Paleozoic rocks
sort of flank up

466
00:25:22,055 --> 00:25:24,725
onto the Precambrian rocks,

467
00:25:25,425 --> 00:25:30,197
which really are
topographically higher as well.

468
00:25:32,633 --> 00:25:34,134
So, in this image,

469
00:25:34,201 --> 00:25:36,937
it looks like the
Precambrian rocks are just one

470
00:25:37,004 --> 00:25:41,475
big gray blob, whereas they are
highly complex.

471
00:25:43,076 --> 00:25:46,113
There's a really interesting
and long Earth history

472
00:25:46,180 --> 00:25:47,447
associated with them.

473
00:25:47,514 --> 00:25:51,151
We are gonna whiz
through this, okay?

474
00:25:51,218 --> 00:25:55,556
And so, let's think about just
those materials

475
00:25:56,123 --> 00:25:58,358
that are delineated on this map.

476
00:25:58,425 --> 00:26:02,763
You can see that Paleozoic cover
that's-- those were the--

477
00:26:02,829 --> 00:26:07,501
those layered rocks in the
previous slide, right?

478
00:26:08,135 --> 00:26:11,672
Okay, so, the oldest rocks
in Wisconsin

479
00:26:11,738 --> 00:26:17,311
are 3 billion or more years old
and associated with the areas

480
00:26:17,978 --> 00:26:21,114
that are labeled
the Archean Superior Continent

481
00:26:21,181 --> 00:26:22,616
and the Marshfield Continent.

482
00:26:22,683 --> 00:26:24,451
So, the distribution
of continents

483
00:26:24,518 --> 00:26:26,787
and ultimately
lithospheric plates,

484
00:26:26,854 --> 00:26:30,157
in the past, it was very
different than what it is today.

485
00:26:30,224 --> 00:26:31,825
And we think that there
were sort of

486
00:26:31,892 --> 00:26:33,393
two different continents,

487
00:26:33,460 --> 00:26:37,798
which we're calling the Superior
and Marshfield Continents, okay?

488
00:26:37,865 --> 00:26:39,766
And in between them,

489
00:26:40,234 --> 00:26:42,402
there would have been
an ocean basin

490
00:26:42,469 --> 00:26:45,839
where iron-rich sediments
were deposited.

491
00:26:45,906 --> 00:26:48,942
So, I talked about those
banded iron formations

492
00:26:49,009 --> 00:26:50,777
previously, right?

493
00:26:50,844 --> 00:26:52,746
It's during this time period

494
00:26:52,813 --> 00:26:55,616
that we think the abandoned
iron formations,

495
00:26:55,682 --> 00:26:59,586
or BIFs that geologists
sometimes call them

496
00:26:59,653 --> 00:27:01,321
were deposited.

497
00:27:01,622 --> 00:27:05,225
Very, very different environment
than today.

498
00:27:05,292 --> 00:27:07,494
We don't think
that there was free oxygen.

499
00:27:07,561 --> 00:27:12,299
As a result, the iron stayed
and dissolved in waters

500
00:27:12,366 --> 00:27:17,137
and was able to precipitate
out with sediments, okay?

501
00:27:17,204 --> 00:27:19,039
There are no places
on Earth

502
00:27:19,106 --> 00:27:24,478
where banded iron formation
are being actively formed today.

503
00:27:24,545 --> 00:27:28,882
Okay, but it worked
3 billion years ago, right?

504
00:27:30,117 --> 00:27:32,085
All right,
at about 2 billion years ago,

505
00:27:32,152 --> 00:27:34,588
we think there was a major
mountain-building event.

506
00:27:34,655 --> 00:27:37,958
And we call this the Penokean
mountain-building event.

507
00:27:38,025 --> 00:27:42,896
And so, the-- those continents
moved closer together.

508
00:27:42,963 --> 00:27:45,632
And a mountain range formed.

509
00:27:46,099 --> 00:27:49,203
For tens of millions of years
afterwards,

510
00:27:49,269 --> 00:27:53,674
that mountain range
was eroded away, okay?

511
00:27:53,740 --> 00:27:55,676
There were other
mountain-building events

512
00:27:55,742 --> 00:27:56,944
as well.

513
00:27:57,010 --> 00:28:01,014
And one that is probably
interesting to you

514
00:28:01,582 --> 00:28:03,851
is the Baraboo mountain-building
event.

515
00:28:03,917 --> 00:28:08,922
We think that was around maybe
1.7 billion years ago,

516
00:28:08,989 --> 00:28:12,893
and that caused the folding
and formation

517
00:28:15,195 --> 00:28:18,999
of what is today
our Baraboo Hills, okay?

518
00:28:20,033 --> 00:28:24,638
The other thing I'll just point
out is the Wolf River complex

519
00:28:24,705 --> 00:28:26,406
that's in red on the slide.

520
00:28:26,473 --> 00:28:29,977
A little bit later,
1.5 billion years ago,

521
00:28:30,043 --> 00:28:32,813
there was emplacement
of igneous rocks

522
00:28:32,880 --> 00:28:36,450
in the subsurface that cooled
pretty slowly,

523
00:28:36,517 --> 00:28:38,785
allowing individual crystals

524
00:28:38,852 --> 00:28:41,321
to be more visible
and interlocking.

525
00:28:41,388 --> 00:28:43,790
You know, rocks
like granite, right?

526
00:28:43,857 --> 00:28:46,627
In fact, our state rock,
the red granite, right?

527
00:28:46,693 --> 00:28:48,395
You can see all
the little crystals.

528
00:28:48,462 --> 00:28:51,064
That's a sign
that there was a magma body

529
00:28:51,131 --> 00:28:53,333
that cooled pretty slowly

530
00:28:53,400 --> 00:28:56,303
and allowed those
interlocking crystals

531
00:28:56,370 --> 00:29:01,308
to come together tightly
and form rocks like granite.

532
00:29:01,375 --> 00:29:03,177
Okay?

533
00:29:03,243 --> 00:29:06,880
Wisconsin also has
a history of volcanism, right?

534
00:29:06,947 --> 00:29:11,084
So, the last major event
that I'll mention is

535
00:29:12,619 --> 00:29:16,089
the area called the
Lake Superior Rift up there.

536
00:29:16,156 --> 00:29:20,727
And in this event,
about 1 billion years ago or so,

537
00:29:21,862 --> 00:29:24,865
we think that the continent
at that time

538
00:29:24,932 --> 00:29:29,770
started what geologists call
rifting, moving apart,

539
00:29:29,837 --> 00:29:31,638
diverging, right?

540
00:29:32,072 --> 00:29:35,642
And volcanism would have been
associated with that.

541
00:29:35,709 --> 00:29:38,712
A similar environment
today is in East Africa.

542
00:29:38,779 --> 00:29:42,382
If you've ever heard of the
East African Rift System, okay?

543
00:29:42,449 --> 00:29:44,751
There's an active rift system

544
00:29:44,818 --> 00:29:48,388
along East Africa
and into the Red Sea.

545
00:29:50,257 --> 00:29:53,961
So, we have modern analogs
for that today.

546
00:29:54,027 --> 00:29:55,295
For whatever reason,

547
00:29:55,362 --> 00:29:59,600
the Lake Superior Rift,
it never continued.

548
00:29:59,666 --> 00:30:01,235
It failed.

549
00:30:01,301 --> 00:30:06,974
And yet, we have evidence of it
in the rock record today, okay?

550
00:30:07,741 --> 00:30:10,477
There were other periods
of volcanism too.

551
00:30:10,544 --> 00:30:12,613
I tried to hit the highlights.

552
00:30:12,679 --> 00:30:16,550
We just covered, like, 3 billion
years of geologic time.

553
00:30:16,617 --> 00:30:19,620
You can go and see these rocks,
you know,

554
00:30:19,686 --> 00:30:23,824
at Devil's Lake
to see the Baraboo Quartzite

555
00:30:24,358 --> 00:30:27,394
and Copper Falls up
in Ashland County.

556
00:30:27,461 --> 00:30:33,333
You can see some of the rift
sediments and volcanics, okay?

557
00:30:33,400 --> 00:30:37,871
All right, let's get into the
Paleozoic, right?

558
00:30:38,772 --> 00:30:41,675
And so, and hopefully
you can see this okay

559
00:30:41,742 --> 00:30:43,076
on the slide,

560
00:30:43,143 --> 00:30:47,147
but in addition to having a
simplified geologic time scale,

561
00:30:47,214 --> 00:30:50,317
I tried to color in time periods

562
00:30:50,384 --> 00:30:54,555
for which we have rock material
in Wisconsin, okay?

563
00:30:54,621 --> 00:30:56,557
So, we just covered
that time period

564
00:30:56,623 --> 00:31:01,195
from 3 billion to about
900 million years ago, okay?

565
00:31:01,261 --> 00:31:04,464
And what
we're gonna look at then

566
00:31:04,531 --> 00:31:08,268
is roughly from, you know,
500 million to, what,

567
00:31:08,335 --> 00:31:13,340
about 400 million years ago,
into the Devonian, okay?

568
00:31:14,241 --> 00:31:17,411
And at this time,
what we call Wisconsin,

569
00:31:17,477 --> 00:31:19,947
it was not in the
northern hemisphere, right?

570
00:31:20,013 --> 00:31:22,216
Remember, the configuration
of lithospheric plates

571
00:31:22,282 --> 00:31:25,118
was very different in the past.

572
00:31:25,185 --> 00:31:26,920
So, it was not
in the northern hemisphere

573
00:31:26,987 --> 00:31:30,991
and it was actually
close to a coastal area.

574
00:31:31,592 --> 00:31:35,963
So, all of these rocks that
are associated with Cambrian,

575
00:31:36,029 --> 00:31:38,732
Ordovician, Silurian,
Devonian time

576
00:31:38,799 --> 00:31:43,537
are representative of marine
or shallow coastal environments.

577
00:31:43,604 --> 00:31:44,838
Okay?

578
00:31:44,905 --> 00:31:47,307
To get a picture
of what I'm talking about,

579
00:31:47,374 --> 00:31:51,979
we're gonna take a look at some
paleogeographic maps, okay?

580
00:31:52,045 --> 00:31:55,349
And so, old geography.
[laughs]

581
00:31:55,415 --> 00:31:59,086
And geologists
always start in the past

582
00:31:59,152 --> 00:32:01,121
and work our way to the present.

583
00:32:01,188 --> 00:32:03,123
If we try to do present
to the past,

584
00:32:03,190 --> 00:32:05,392
we get very confused, okay?

585
00:32:05,459 --> 00:32:08,228
So, we'll go through this
a couple times, right?

586
00:32:08,295 --> 00:32:10,797
But we're starting
in the Cambrian.

587
00:32:10,864 --> 00:32:14,902
And you can see, most of the
continental masses are south

588
00:32:14,968 --> 00:32:18,038
and, you know,
south of the equator here.

589
00:32:18,105 --> 00:32:19,373
One note, too.

590
00:32:19,439 --> 00:32:23,010
Remember, continents don't slide
around over the mantle.

591
00:32:23,076 --> 00:32:25,445
Lithospheric plates
slide around.

592
00:32:25,512 --> 00:32:27,714
And lithospheric plates

593
00:32:27,781 --> 00:32:29,716
can have continental
crustal material

594
00:32:29,783 --> 00:32:32,319
and oceanic crustal material.

595
00:32:32,386 --> 00:32:33,854
It's important to remember

596
00:32:33,921 --> 00:32:36,223
it's not the continents,
really, that are moving around.

597
00:32:36,290 --> 00:32:38,892
It's these larger,
larger plates.

598
00:32:38,959 --> 00:32:40,627
Okay?

599
00:32:41,228 --> 00:32:43,130
Okay, so, Cambrian.

600
00:32:43,463 --> 00:32:45,399
Oh, the other thing to point out
is,

601
00:32:45,465 --> 00:32:47,634
up in the upper
left-hand corner,

602
00:32:47,701 --> 00:32:50,170
you can
kind of see some yellow outlines

603
00:32:50,237 --> 00:32:53,040
of today's geography, right?

604
00:32:53,440 --> 00:32:56,009
The state outlines up there,
okay?

605
00:32:56,076 --> 00:32:57,611
So, kind of keep your eye
on that

606
00:32:57,678 --> 00:33:00,347
because that's what
we're kind of working towards.

607
00:33:00,414 --> 00:33:02,716
All right, so, Cambrian.

608
00:33:04,251 --> 00:33:07,054
Here we are in the Ordovician.

609
00:33:07,588 --> 00:33:09,256
Silurian.

610
00:33:10,157 --> 00:33:12,292
430 million years ago.

611
00:33:12,659 --> 00:33:14,328
Devonian.

612
00:33:14,928 --> 00:33:17,831
Some of that material is
kind of coming together

613
00:33:17,898 --> 00:33:19,566
a little bit more.

614
00:33:20,834 --> 00:33:23,036
Here in the Permian,
I start to see things

615
00:33:23,103 --> 00:33:25,072
that look a little bit familiar
to me.

616
00:33:25,138 --> 00:33:29,543
But, granted,
I've seen these before, right?

617
00:33:29,610 --> 00:33:30,944
But you will too.

618
00:33:31,011 --> 00:33:35,449
So, here we are in the Permian,
late Cretaceous.

619
00:33:35,516 --> 00:33:37,985
Starting to recognize things?

620
00:33:38,051 --> 00:33:40,187
And the present, okay?

621
00:33:41,221 --> 00:33:44,358
So, go through it
real fast again.

622
00:33:45,792 --> 00:33:47,461
Okay, Cambrian.

623
00:33:54,434 --> 00:33:57,171
So, while it's really hard
to pick out exactly

624
00:33:57,237 --> 00:33:58,505
where Wisconsin would be

625
00:33:58,572 --> 00:34:01,108
on these
Paleogeographic maps,

626
00:34:01,175 --> 00:34:03,577
hopefully you get a sense
that there was--

627
00:34:03,644 --> 00:34:07,781
there was a lot
of coastal property [laughs]

628
00:34:08,415 --> 00:34:11,251
as the continents
and lithospheric plates

629
00:34:11,318 --> 00:34:13,420
migrated northward, okay?

630
00:34:13,487 --> 00:34:15,856
And that would have been
the environment.

631
00:34:15,923 --> 00:34:17,424
So, what do these rocks
look like?

632
00:34:17,491 --> 00:34:19,526
And where can we see them?

633
00:34:19,593 --> 00:34:24,097
The Cambrian rocks, there's
a lot of sandstones, okay?

634
00:34:24,164 --> 00:34:26,967
And they're very quartz rich,
okay?

635
00:34:27,034 --> 00:34:29,203
If you know the mineral quartz,
right?

636
00:34:29,269 --> 00:34:31,839
A lot of silicon and oxygen.

637
00:34:32,206 --> 00:34:34,208
Close up,
you can see that many of them

638
00:34:34,274 --> 00:34:36,510
are really what we call clean.

639
00:34:36,577 --> 00:34:38,812
There's not much else in 'em
besides quartz.

640
00:34:38,879 --> 00:34:40,380
They're really well rounded.

641
00:34:40,447 --> 00:34:42,216
We call that mature
because it means

642
00:34:42,282 --> 00:34:43,917
they've really
been tossed around

643
00:34:43,984 --> 00:34:45,752
and edges have been worn off.

644
00:34:45,819 --> 00:34:49,056
They're almost spherical, right?

645
00:34:50,157 --> 00:34:53,327
And then, you can see what
some rock outcrops look like.

646
00:34:53,393 --> 00:34:56,296
It's this rock material
that is really good

647
00:34:56,363 --> 00:34:58,031
for frac sands.

648
00:34:58,765 --> 00:35:00,400
Okay.

649
00:35:00,467 --> 00:35:05,372
And there are exposures
in southwestern Wisconsin.

650
00:35:05,939 --> 00:35:09,843
But as you drive northward
to central Wisconsin,

651
00:35:09,910 --> 00:35:14,915
you'll see some of the active
mines that are extracting

652
00:35:14,982 --> 00:35:17,217
the quartz-rich sands.

653
00:35:20,254 --> 00:35:22,489
Here's that outcrop
I showed you before,

654
00:35:22,556 --> 00:35:24,391
real close to Dickeyville,
right before--

655
00:35:24,458 --> 00:35:26,727
right between Dickeyville
and Platteville

656
00:35:26,793 --> 00:35:29,296
in southwest Wisconsin.

657
00:35:29,363 --> 00:35:32,499
And a lot
of the Ordovician rocks,

658
00:35:33,233 --> 00:35:35,269
slightly deeper water
environment.

659
00:35:35,335 --> 00:35:38,338
They have a lot
of calcium carbonate in them.

660
00:35:38,405 --> 00:35:40,974
So, limestone or dolomite,

661
00:35:41,975 --> 00:35:44,878
which is a calcium
magnesium carbonate.

662
00:35:44,945 --> 00:35:47,214
There are some shales, okay?

663
00:35:47,281 --> 00:35:50,517
And you can see
that layered nature

664
00:35:50,951 --> 00:35:52,953
in this rock outcrop.

665
00:35:55,389 --> 00:35:57,191
Silurian rocks.

666
00:35:57,257 --> 00:36:00,360
Well, you'd need to go over
to the Door Peninsula

667
00:36:00,427 --> 00:36:01,862
to see them exposed.

668
00:36:01,929 --> 00:36:05,632
They're buried in most places
in eastern Wisconsin.

669
00:36:05,699 --> 00:36:10,137
But if you go to Peninsula
State Park and Cape Point

670
00:36:10,204 --> 00:36:11,839
in Door County,

671
00:36:11,905 --> 00:36:14,174
that's the Silurian dolomite,
and it's,

672
00:36:14,241 --> 00:36:19,379
and it's also sometimes called
the Niagaran dolomite.

673
00:36:20,514 --> 00:36:24,318
Okay, so, recall that now,
in Wisconsin,

674
00:36:26,353 --> 00:36:29,389
we have what's called
an unconformity.

675
00:36:29,456 --> 00:36:34,027
And what that means is we just
simply do not have rock material

676
00:36:34,094 --> 00:36:37,564
that represents
a vast time period, okay?

677
00:36:37,631 --> 00:36:38,765
There's not a gap in time.

678
00:36:38,832 --> 00:36:39,933
Time happened.

679
00:36:40,000 --> 00:36:42,436
There's a gap
in the rock record, right?

680
00:36:42,503 --> 00:36:46,740
And the next material
that covers much of Wisconsin

681
00:36:46,807 --> 00:36:51,712
is largely eroded material,
transported material,

682
00:36:52,880 --> 00:36:57,050
and deposited material
by glaciers and also streams.

683
00:36:57,117 --> 00:36:58,785
Okay?

684
00:36:59,520 --> 00:37:05,859
So, Wisconsin's glacial past had
many phases of glacial activity.

685
00:37:05,926 --> 00:37:10,163
Major advance of an ice sheet,
major retreat, okay?

686
00:37:10,230 --> 00:37:13,400
And this map shows some
of the major phases

687
00:37:13,467 --> 00:37:18,238
of glaciation, called the
Pre-Illinoian, the Illinoian,

688
00:37:18,305 --> 00:37:20,140
and then the Wisconsinan
glaciation.

689
00:37:20,207 --> 00:37:22,743
And it's named
the Wisconsinan glaciation

690
00:37:22,809 --> 00:37:24,845
because we have such
great examples

691
00:37:24,912 --> 00:37:27,581
of landforms and materials,

692
00:37:28,015 --> 00:37:30,017
landforms that were formed
and materials

693
00:37:30,083 --> 00:37:34,588
that were deposited during
that particular glacial phase.

694
00:37:34,655 --> 00:37:35,756
Okay?

695
00:37:35,822 --> 00:37:38,992
Even during each one
of these phases,

696
00:37:39,059 --> 00:37:43,730
there were multiple advances
and retreat of the glacial ice.

697
00:37:43,797 --> 00:37:45,866
So, the next slide here,

698
00:37:45,933 --> 00:37:48,435
we're gonna look at a video
of this,

699
00:37:48,502 --> 00:37:51,972
of the late Wisconsinan
glacial time

700
00:37:53,507 --> 00:37:56,877
and really just
the last 30,000 years or so.

701
00:37:56,944 --> 00:37:59,947
So, I'm going to start
the video.

702
00:38:01,048 --> 00:38:02,716
There we go.

703
00:38:04,585 --> 00:38:08,655
Okay, you can see the ice
advance across the landscape.

704
00:38:08,722 --> 00:38:12,526
Doesn't make it
to southwest Wisconsin.

705
00:38:13,527 --> 00:38:18,498
Large lakes formed at the margin
of the ice at times.

706
00:38:20,734 --> 00:38:23,136
And they disappear
and drain away

707
00:38:23,203 --> 00:38:26,006
as the ice retreats and melts.

708
00:38:27,975 --> 00:38:33,213
Sometimes it retreats
pretty far outside of Wisconsin.

709
00:38:34,715 --> 00:38:38,752
Right, and at about 11,000
or 10,000 years ago,

710
00:38:38,819 --> 00:38:42,189
ice exited Wisconsin
for the last time.

711
00:38:42,256 --> 00:38:45,192
The last remnants
of that ice sheet

712
00:38:45,259 --> 00:38:48,362
probably disappeared
from Canada,

713
00:38:48,428 --> 00:38:53,100
Hudson Bay area, maybe
around 7,000 years ago or so.

714
00:38:53,166 --> 00:38:54,635
Okay?

715
00:38:54,701 --> 00:38:58,438
And so, again,
it's the Wisconsinan glaciation

716
00:38:58,505 --> 00:39:01,875
because we have such
great examples of landforms.

717
00:39:01,942 --> 00:39:03,777
On the right-hand side,

718
00:39:03,844 --> 00:39:07,481
there's an image of these
brown lines across the state.

719
00:39:07,548 --> 00:39:09,449
Those are called moraines.

720
00:39:09,516 --> 00:39:13,854
They're ridges of material that,
in this case,

721
00:39:14,888 --> 00:39:18,125
if you look at the
outermost ridge,

722
00:39:18,192 --> 00:39:20,761
we would call that a terminal
moraine because that's the--

723
00:39:20,827 --> 00:39:23,730
that's sort of the farthest
that the ice advanced.

724
00:39:23,797 --> 00:39:25,566
And as it paused there,

725
00:39:25,632 --> 00:39:30,537
this debris-rich ice material
melted out of the ice.

726
00:39:31,238 --> 00:39:32,840
Sometimes it sort of was
bulldozed

727
00:39:32,906 --> 00:39:35,042
in front of the ice too.

728
00:39:35,542 --> 00:39:40,113
In any case, ridges were
developed at that margin, okay?

729
00:39:40,180 --> 00:39:41,548
And if it's
the outermost one,

730
00:39:41,615 --> 00:39:43,217
that's the terminal moraine.

731
00:39:43,283 --> 00:39:45,085
But then, you can see
that there are,

732
00:39:45,152 --> 00:39:48,255
there are also sort of
somewhat concentric lines

733
00:39:48,322 --> 00:39:50,090
as you go northward.

734
00:39:50,157 --> 00:39:52,259
I would call those
recessional moraines.

735
00:39:52,326 --> 00:39:54,561
So, just like
in the previous video, right,

736
00:39:54,628 --> 00:39:58,999
we saw that sometimes the ice
retreated, paused a little bit,

737
00:39:59,066 --> 00:40:01,702
may have built
up a little moraine, right?

738
00:40:01,768 --> 00:40:03,504
Maybe retreated a bit.

739
00:40:03,570 --> 00:40:06,907
Maybe re-advanced,
built up a moraine in front

740
00:40:06,974 --> 00:40:09,176
before finally retreating.

741
00:40:09,243 --> 00:40:10,377
Okay?

742
00:40:10,444 --> 00:40:12,613
Yet, in southwest Wisconsin,

743
00:40:12,679 --> 00:40:16,083
not only in the Wisconsinan
glaciation, during that phase,

744
00:40:16,149 --> 00:40:17,851
but also previous phases,

745
00:40:17,918 --> 00:40:20,187
we don't have evidence
of glacial activity.

746
00:40:20,254 --> 00:40:21,622
And so,
that's what we call

747
00:40:21,688 --> 00:40:24,258
the Driftless Area of Wisconsin.

748
00:40:24,324 --> 00:40:27,427
And its topography is
much more defined

749
00:40:27,494 --> 00:40:31,965
by stream erosion and valleys
and ridges, okay?

750
00:40:32,766 --> 00:40:33,867
Some other landforms.

751
00:40:33,934 --> 00:40:37,771
There's a drumlin up
in the upper image.

752
00:40:37,838 --> 00:40:40,274
That's also what I showed you
at the very beginning,

753
00:40:40,340 --> 00:40:44,444
when there were crops that were
concentric around that hill.

754
00:40:44,511 --> 00:40:46,647
These are streamlined hills

755
00:40:46,713 --> 00:40:50,751
that indicate the former
flow direction of ice.

756
00:40:50,817 --> 00:40:52,252
Okay?

757
00:40:52,319 --> 00:40:55,155
And we have a lot, right,
in sort of eastern

758
00:40:55,222 --> 00:40:57,457
and central Wisconsin.

759
00:40:57,991 --> 00:41:03,096
The bottom two images, one is
a kame and one is an esker.

760
00:41:03,163 --> 00:41:06,567
And both of these landforms
form in environments

761
00:41:06,633 --> 00:41:11,405
where there's just a lot
of glacial meltwater streams.

762
00:41:11,471 --> 00:41:12,673
Okay?

763
00:41:12,739 --> 00:41:17,311
And so, for a kame,
near the margin of the glacier

764
00:41:17,377 --> 00:41:19,346
as it's melting
and wasting away,

765
00:41:19,413 --> 00:41:21,815
there might be a channel

766
00:41:21,882 --> 00:41:24,751
that starts
to drain water from the top.

767
00:41:24,818 --> 00:41:26,353
And just like being
at the beach

768
00:41:26,420 --> 00:41:28,689
when you start
to make a little,

769
00:41:28,755 --> 00:41:32,359
make a little hill, right,
by dripping sediment, right,

770
00:41:32,426 --> 00:41:34,361
a kame is a conical hill.

771
00:41:34,428 --> 00:41:36,096
It's largely sand and gravel.

772
00:41:36,163 --> 00:41:38,932
And it's because it formed
at the base

773
00:41:38,999 --> 00:41:41,702
of one of these drainages.

774
00:41:41,768 --> 00:41:43,036
Okay?

775
00:41:43,103 --> 00:41:47,708
An esker is also related
to subglacial drainage.

776
00:41:47,774 --> 00:41:50,444
So, if there's a channel that
is bringing water

777
00:41:50,511 --> 00:41:53,413
from that-- the edge of the ice,

778
00:41:56,116 --> 00:41:59,753
right, forward
into a meltwater environment,

779
00:41:59,820 --> 00:42:02,356
that channel might
be weaving back and forth

780
00:42:02,422 --> 00:42:06,927
beneath the glacial ice,
carrying sediment with it, okay?

781
00:42:06,994 --> 00:42:08,795
But then, once all the--

782
00:42:08,862 --> 00:42:12,332
once all the ice melts,
you're left with the sediment

783
00:42:12,399 --> 00:42:13,867
that was in the channel.

784
00:42:13,934 --> 00:42:18,772
And now it's a windy ridge
on the landscape, okay?

785
00:42:18,839 --> 00:42:21,475
If you've ever been
to the Kettle Moraine,

786
00:42:21,542 --> 00:42:24,578
the northern unit of the
Kettle Moraine State Forest,

787
00:42:24,645 --> 00:42:25,746
you'll see these features.

788
00:42:25,812 --> 00:42:28,415
That's where
these pictures were taken.

789
00:42:28,482 --> 00:42:30,150
Okay.

790
00:42:31,051 --> 00:42:32,386
Okay.

791
00:42:32,452 --> 00:42:35,556
So, now I am going to tell
you a little bit about the work

792
00:42:35,622 --> 00:42:39,026
of the Wisconsin Geological
and Natural History Survey.

793
00:42:39,092 --> 00:42:41,228
And so, our mission...

794
00:42:42,329 --> 00:42:44,898
As I said, we are part
of the Division of Extension

795
00:42:44,965 --> 00:42:46,400
at UW-Madison,

796
00:42:46,466 --> 00:42:49,803
and our mission is
to conduct education,

797
00:42:49,870 --> 00:42:53,440
outreach, and applied research
activities on the geology,

798
00:42:53,507 --> 00:42:56,543
mineral, and water
resources of the state.

799
00:42:56,610 --> 00:43:01,715
We do that to provide baseline
information for decision-making,

800
00:43:01,782 --> 00:43:05,285
informed decision-making
by local government,

801
00:43:05,352 --> 00:43:08,522
county government, tribal
government, state government,

802
00:43:08,589 --> 00:43:11,792
industry,
the agricultural sector.

803
00:43:11,859 --> 00:43:14,862
We don't have any policy forming

804
00:43:16,196 --> 00:43:20,300
or regulatory enforcement
obligations.

805
00:43:20,367 --> 00:43:24,171
We are there to provide that
information

806
00:43:24,972 --> 00:43:27,674
for decision-making, okay?

807
00:43:27,741 --> 00:43:31,979
We have about 27 staff members,
and this is us.

808
00:43:32,646 --> 00:43:35,816
Once a year, we take a field
trip, a staff field trip.

809
00:43:35,883 --> 00:43:36,984
This is from last fall.

810
00:43:37,050 --> 00:43:39,453
It's in the Baraboo area.

811
00:43:39,520 --> 00:43:41,655
On the left-hand side,

812
00:43:42,055 --> 00:43:46,393
there's a pie chart that shows
areas of expertise of our staff.

813
00:43:46,460 --> 00:43:49,730
So, we have a bunch
of hydrogeologists, right,

814
00:43:49,796 --> 00:43:53,901
studying groundwater,
bedrock geologists,

815
00:43:53,967 --> 00:43:56,904
Quaternary geologists, that's
that most recent time period.

816
00:43:56,970 --> 00:44:01,708
So, these are the folks
who study glaciers and streams

817
00:44:01,775 --> 00:44:03,911
and those processes.

818
00:44:03,977 --> 00:44:07,948
We have a large staff of--
large for us-- [chuckles]

819
00:44:08,015 --> 00:44:12,352
staff of geographic
information scientists.

820
00:44:12,419 --> 00:44:13,654
At a base level,

821
00:44:13,720 --> 00:44:18,759
you can think about this
as digital cartography, okay?

822
00:44:18,825 --> 00:44:20,694
Because we make a lot of maps.

823
00:44:20,761 --> 00:44:24,298
But it's so much more because
it's all of the spatial analysis

824
00:44:24,364 --> 00:44:28,802
that can happen with these
electronic geological data sets

825
00:44:28,869 --> 00:44:31,438
and modeling, computer modeling.

826
00:44:31,505 --> 00:44:36,343
So, important folks in the
office as well as outreach,

827
00:44:36,410 --> 00:44:40,480
archival geological curation
specialists.

828
00:44:41,682 --> 00:44:47,254
We have folks who manage our
databases and publications.

829
00:44:47,321 --> 00:44:51,892
And then, there are
a few administrators, right?

830
00:44:52,226 --> 00:44:54,595
We're located about a mile west

831
00:44:54,661 --> 00:44:58,131
of the UW-Madison campus
in Madison.

832
00:44:58,732 --> 00:45:00,968
But then, we have
a second facility too.

833
00:45:01,034 --> 00:45:03,737
It's our core repository.

834
00:45:03,804 --> 00:45:08,041
So, rock core
cylindrical samples collected

835
00:45:09,109 --> 00:45:12,880
through drilling methods
have been collected

836
00:45:12,946 --> 00:45:17,618
for decades and decades
and decades in Wisconsin.

837
00:45:18,719 --> 00:45:21,955
Whether it's
for mining exploration,

838
00:45:22,022 --> 00:45:25,692
whether it is
for foundation drilling,

839
00:45:27,995 --> 00:45:32,099
the Department of Transportation
sometimes collects core

840
00:45:32,165 --> 00:45:36,303
when they're establishing
strength, right, for bridges.

841
00:45:36,370 --> 00:45:39,439
Each one of the dots
represents a location

842
00:45:39,506 --> 00:45:44,745
where we have core material
stored at our core repository

843
00:45:44,811 --> 00:45:46,180
out in Mount Horeb.

844
00:45:46,246 --> 00:45:50,884
I like to call this facility
Wisconsin's subsurface library.

845
00:45:50,951 --> 00:45:55,222
These materials, it's
really hard to put a value on.

846
00:45:55,289 --> 00:45:58,992
It's expensive
to collect core, right?

847
00:45:59,059 --> 00:46:01,094
We don't want
to just toss it out.

848
00:46:01,161 --> 00:46:03,764
We don't know what tomorrow's
questions are gonna be.

849
00:46:03,830 --> 00:46:04,932
We don't know

850
00:46:04,998 --> 00:46:09,236
what new instrumentation
might be available

851
00:46:09,770 --> 00:46:13,073
so that we can analyze it
in different ways.

852
00:46:13,140 --> 00:46:15,943
And so, we want to preserve it.

853
00:46:16,844 --> 00:46:18,612
We also have cuttings.

854
00:46:18,679 --> 00:46:20,614
Cuttings-- So, sometimes
it's too expensive

855
00:46:20,681 --> 00:46:22,649
to collect core, right?

856
00:46:22,716 --> 00:46:25,552
And so, we use
a drilling technique

857
00:46:25,619 --> 00:46:26,753
that's called air rotary.

858
00:46:26,820 --> 00:46:30,190
It's got a tri-cone roller bit
on it, and it--

859
00:46:30,257 --> 00:46:34,461
and it basically crushes up
the rock as you drill downward.

860
00:46:34,528 --> 00:46:38,432
And then, little chips of rock
fly out the borehole with water.

861
00:46:38,498 --> 00:46:43,303
And a geologist leans in
with a vegetable strainer,

862
00:46:44,805 --> 00:46:49,476
to-- this is true-- with--
to catch that material.

863
00:46:50,310 --> 00:46:55,449
Because little chips of rock are
better than no samples, right?

864
00:46:55,516 --> 00:46:58,018
We put them in baggies,
we label them,

865
00:46:58,085 --> 00:47:01,054
we geolocate them,
and we study them.

866
00:47:01,121 --> 00:47:03,357
And that's what cuttings are.

867
00:47:03,423 --> 00:47:06,393
And then, geologists tend
to pick up rocks

868
00:47:06,460 --> 00:47:07,794
when we're in the field.

869
00:47:07,861 --> 00:47:09,596
We call those hand samples.

870
00:47:09,663 --> 00:47:12,099
And so, we have
over 15,000 hand samples

871
00:47:12,165 --> 00:47:14,635
from across the state too.

872
00:47:14,701 --> 00:47:18,305
We offer tours
of the core repository.

873
00:47:18,372 --> 00:47:21,475
Okay,
and what do we actually do?

874
00:47:21,542 --> 00:47:23,343
We do a lot of mapping.

875
00:47:23,410 --> 00:47:27,548
So, some of our mapping
is geologic mapping.

876
00:47:28,081 --> 00:47:29,183
And you might think, okay,

877
00:47:29,249 --> 00:47:31,518
the survey's been around
for over 125 years.

878
00:47:31,585 --> 00:47:33,153
Don't you have
the state mapped yet?

879
00:47:33,220 --> 00:47:34,755
We don't.
[audience member laughs]

880
00:47:34,821 --> 00:47:37,124
Sometimes we redo areas too.

881
00:47:37,191 --> 00:47:39,459
But here's our progress, right?

882
00:47:39,526 --> 00:47:41,929
And there are areas
that do not have

883
00:47:41,995 --> 00:47:46,300
bedrock geologic
mapping completed yet, right?

884
00:47:46,366 --> 00:47:50,137
We tend to do a lot
of mapping at the county scale.

885
00:47:50,204 --> 00:47:52,139
We work with county partners.

886
00:47:52,206 --> 00:47:55,008
It's also a really
useful level of detail

887
00:47:55,075 --> 00:47:59,346
for a variety
of land use planning questions,

888
00:47:59,413 --> 00:48:01,381
water resources questions.

889
00:48:01,448 --> 00:48:05,452
So, we often--
We often map counties, okay.

890
00:48:06,153 --> 00:48:09,590
We rarely just produce
a geologic map.

891
00:48:09,656 --> 00:48:13,560
We often produce lots
of other layers too.

892
00:48:14,027 --> 00:48:16,396
And I've got a list of layers

893
00:48:16,463 --> 00:48:19,233
for this particular study
from Jefferson County,

894
00:48:19,299 --> 00:48:22,636
which was published
in March of '24.

895
00:48:23,303 --> 00:48:24,671
Depth to bedrock surface.

896
00:48:24,738 --> 00:48:26,073
This is a area of the state

897
00:48:26,139 --> 00:48:28,175
that's completely covered
by glacial material.

898
00:48:28,242 --> 00:48:31,345
So, how deep is
the bedrock surface?

899
00:48:31,411 --> 00:48:32,813
And then, we map out

900
00:48:32,880 --> 00:48:37,284
the elevation
of different geologic layers.

901
00:48:37,351 --> 00:48:41,688
And so, that's what each one
of the other layers are,

902
00:48:41,755 --> 00:48:45,526
as well as trying
to tie hydrogeologic properties

903
00:48:45,592 --> 00:48:49,696
to these rock materials
because they serve as aquifers.

904
00:48:49,763 --> 00:48:52,499
This is what a map looks like.

905
00:48:52,566 --> 00:48:56,136
This is remarkable because,
as I said,

906
00:48:56,970 --> 00:49:02,643
this area is almost completely
covered by glacial deposits.

907
00:49:03,310 --> 00:49:06,313
So, we use a lot
of borehole data.

908
00:49:07,080 --> 00:49:10,317
Sometimes we drill
new boreholes.

909
00:49:11,051 --> 00:49:14,922
But more often,
we use existing records

910
00:49:14,988 --> 00:49:17,257
from private well records.

911
00:49:17,324 --> 00:49:18,992
So, if any of you

912
00:49:19,326 --> 00:49:23,197
have your own private well
at your home,

913
00:49:23,263 --> 00:49:26,300
the record
is stored in a database,

914
00:49:26,366 --> 00:49:28,135
and we look at the geology

915
00:49:28,202 --> 00:49:32,673
that the driller recorded,
and we also make cross-sections.

916
00:49:32,739 --> 00:49:35,309
So, this is a much more
detailed cross-section, right,

917
00:49:35,375 --> 00:49:38,278
than what I showed you
across the entire state

918
00:49:38,345 --> 00:49:40,013
at the beginning.

919
00:49:40,914 --> 00:49:43,083
For glacial materials,

920
00:49:43,150 --> 00:49:46,520
we also do statewide mapping,
not just county scale, right?

921
00:49:46,587 --> 00:49:47,721
And I like to show this

922
00:49:47,788 --> 00:49:51,391
because in terms
of glacial geologic mapping,

923
00:49:51,458 --> 00:49:54,061
a geologist named
T.C. Chamberlin

924
00:49:54,127 --> 00:49:58,031
first mapped the glacial geology
in 1881.

925
00:49:58,999 --> 00:50:03,437
And you can see that the shape
of the glacial formations,

926
00:50:03,504 --> 00:50:07,107
like, he did a pretty good job,
right? [laughs]

927
00:50:07,174 --> 00:50:10,511
That map wasn't updated
until 1976.

928
00:50:11,345 --> 00:50:13,747
And then, just last year,

929
00:50:13,814 --> 00:50:19,052
we published a new Quaternary
Geology of Wisconsin map.

930
00:50:19,119 --> 00:50:22,789
And again, all of our map
products are available free

931
00:50:22,856 --> 00:50:25,526
for download at our website.

932
00:50:27,394 --> 00:50:31,331
We also do county scale
glacial geologic mapping too.

933
00:50:31,398 --> 00:50:34,468
And I thought I would just show
an example from Burnett County.

934
00:50:34,535 --> 00:50:38,238
Again, you can see our progress
throughout the state.

935
00:50:38,305 --> 00:50:40,641
We have a lot in progress,
[laughs]

936
00:50:40,707 --> 00:50:43,210
but making pretty good progress
at the county scale

937
00:50:43,277 --> 00:50:47,414
for the glacial
and surficial geologic mapping.

938
00:50:49,316 --> 00:50:52,452
And we do a lot
of groundwater-related work.

939
00:50:52,519 --> 00:50:57,624
Just one example is a county
hydrologic atlas, okay?

940
00:50:57,691 --> 00:51:00,294
And again, just finished this
for Burnett County

941
00:51:00,360 --> 00:51:02,696
in the northwestern part
of the state.

942
00:51:02,763 --> 00:51:07,467
We make use of well construction
reports, again,

943
00:51:07,534 --> 00:51:09,570
like, we really rely on these.

944
00:51:09,636 --> 00:51:11,038
And you can see
the distribution,

945
00:51:11,104 --> 00:51:13,941
all those little dots
in Burnett County.

946
00:51:14,007 --> 00:51:17,678
Each one is a private well
record, okay?

947
00:51:18,145 --> 00:51:22,182
And from that, we're able to,
along with field work,

948
00:51:22,249 --> 00:51:25,052
develop a whole suite of maps.

949
00:51:26,520 --> 00:51:29,690
Here's an image of one of these
well construction reports.

950
00:51:29,756 --> 00:51:32,259
And if you can see on the
right-hand side,

951
00:51:32,326 --> 00:51:35,062
you can see that there's
a series of descriptions

952
00:51:35,128 --> 00:51:38,866
for geologic material
that the well driller recorded.

953
00:51:38,932 --> 00:51:42,202
There's also a static water
level at the time of drilling.

954
00:51:42,269 --> 00:51:45,606
We use that
for water table mapping.

955
00:51:45,672 --> 00:51:47,774
So, again, those records,

956
00:51:47,841 --> 00:51:50,777
sometimes we convert that
into a depth to bedrock

957
00:51:50,844 --> 00:51:53,347
if the well hits
the bedrock surface, right,

958
00:51:53,413 --> 00:51:55,015
then we can map that out.

959
00:51:55,082 --> 00:51:58,118
Other times, we map
the depth to the water table

960
00:51:58,185 --> 00:52:00,654
or contour the water table

961
00:52:01,188 --> 00:52:04,658
and make a water table
elevation map.

962
00:52:05,626 --> 00:52:08,362
We also map
groundwater recharge.

963
00:52:08,428 --> 00:52:10,998
So, groundwater recharge.

964
00:52:11,331 --> 00:52:14,001
There's precipitation, right,

965
00:52:14,067 --> 00:52:16,236
that falls onto the
land surface.

966
00:52:16,303 --> 00:52:20,574
Some of that precipitation
gets utilized by plants.

967
00:52:20,641 --> 00:52:24,211
Some of it runs off,
some of it evaporates, right?

968
00:52:24,278 --> 00:52:27,814
That's the evapotranspiration
that's shown in the diagram.

969
00:52:27,881 --> 00:52:31,118
But some of it infiltrates
through the soil zone

970
00:52:31,185 --> 00:52:33,253
and makes it to the water table.

971
00:52:33,320 --> 00:52:36,990
That's recharging our aquifers,
okay?

972
00:52:37,457 --> 00:52:39,693
And you know, we--
sometimes we'll talk about,

973
00:52:39,760 --> 00:52:42,196
oh, we had a one-inch rainfall,
right?

974
00:52:42,262 --> 00:52:45,866
That's one inch everywhere
on the landscape, right?

975
00:52:45,933 --> 00:52:48,368
We talk about recharge
in the same sense.

976
00:52:48,435 --> 00:52:52,372
So, how much recharge do we get
in a given year, right?

977
00:52:52,439 --> 00:52:56,043
Well, let's say you get
roughly 30 to 32 inches

978
00:52:56,109 --> 00:52:57,611
of precipitation.

979
00:52:57,678 --> 00:53:02,149
A good back-of-the-envelope
estimate for recharge

980
00:53:02,216 --> 00:53:07,621
might be somewhere between
a quarter and a third of that.

981
00:53:07,688 --> 00:53:08,856
Okay?

982
00:53:08,922 --> 00:53:12,860
And so, you can see,
for Burnett County, the average,

983
00:53:12,926 --> 00:53:18,198
the mean is about seven inches
per year of recharge.

984
00:53:20,701 --> 00:53:23,237
And then, finally,
all of those maps get overlaid,

985
00:53:23,303 --> 00:53:28,041
and we produce maps that show
the susceptibility of our water,

986
00:53:28,108 --> 00:53:29,543
our buried groundwater,

987
00:53:29,610 --> 00:53:33,280
our aquifer systems
to contamination, okay?

988
00:53:33,347 --> 00:53:34,781
And so, for example,

989
00:53:34,848 --> 00:53:37,618
where you have
a high recharge rate,

990
00:53:37,684 --> 00:53:40,020
that aquifer might be
a little bit more susceptible,

991
00:53:40,087 --> 00:53:41,655
right, to contamination.

992
00:53:41,722 --> 00:53:44,825
Where there's a really
shallow depth to water,

993
00:53:44,892 --> 00:53:47,561
higher susceptibility
to contamination, right?

994
00:53:47,628 --> 00:53:49,730
So, we use all of these together

995
00:53:49,796 --> 00:53:53,934
and we write up a technical
report and we publish it,

996
00:53:54,001 --> 00:53:56,570
and it's free for download.

997
00:53:56,637 --> 00:53:58,772
And so much more, okay?

998
00:53:59,173 --> 00:54:03,443
And so, you can find
a lot more on our website,

999
00:54:03,510 --> 00:54:05,479
which is up there on the top.

1000
00:54:05,546 --> 00:54:08,549
Each year, we write a year
in review

1001
00:54:08,615 --> 00:54:11,151
where we summarize highlights,

1002
00:54:11,218 --> 00:54:15,322
and there's lots of
great information at the Survey.

1003
00:54:15,389 --> 00:54:18,292
So, thank you
for listening tonight.

1004
00:54:18,358 --> 00:54:20,427
It's been a pleasure being here.

1005
00:54:20,494 --> 00:54:23,463
And, yeah, thank you
for coming out to learn

1006
00:54:23,530 --> 00:54:25,232
about the geology of Wisconsin.

1007
00:54:25,299 --> 00:54:27,267
[audience applauds]