- Today, we are pleased to introduce David M. Mickelson
as part of the Wisconsin History 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.
David M. Mickelson was a professor
in the Department of Geology and Geophysics
at the University of Wisconsin Madison for over 30 years.
In his time at the UW he taught, among other things,
glacial geology, geomorphology,
and the geology of the national parks.
His interests are in modern glacial processes,
glacial deposits and landscapes in the Midwest,
and coastal processes along the Great Lakes.
Mickelson and his students have worked on the genesis
of glacial deposits around the globe,
from Argentina and Tibet
to the states of Alaska and Wisconsin.
And he is also the author of Geology of the Ice Age
National Scenic Trail,
which is a book available in our museum store.
Here to share how southern Wisconsin's
glaciated landscape came to be what it is today,
please join me in welcoming David M. Mickelson.
(audience applauding)
Thank you.
Well, as you've just heard, I'm a glacial geologist,
and I'm interested in the glacial landscape of Wisconsin,
among other things.
And today I'm going to not talk just about
the landscape but a little about the tools that we use.
I'll give you a little historical perspective
of what people could see when they were doing
mapping a hundred years ago
compared to what we can see now, and, in particular,
introduce this fairly new remote sensing technique
called LiDAR, which is a combination of light and radar,
that produces really high resolution images
of the landscape.
And these are drumlins in northeastern Dane County.
And you'll see some even more spectacular images
as we go along.
So, let's proceed.
First, I think all of you probably know but just in case,
we are in Wisconsin right at the very southern edge
of the Laurentide Ice Sheet,
this huge ice sheet that's stretched from the Atlantic Ocean
to the Pacific Ocean, all the way across the,
well, it was actually sea ice over the Arctic Ocean.
But you could have stepped onto the glacier right here
outside of Madison and walked all the way across
to southern Russia, across the northern polar area,
without ever getting off the ice.
So it was a huge amount of ice,
and we are located just at the very edge of it.
This was in the last glaciation.
It's called the Wisconsin glaciation.
It's called the Wisconsin glaciation
because the glacial features in Wisconsin
are particularly well developed,
and also it didn't hurt that TC Chamberlin,
who was instrumental in naming the Wisconsin glaciation,
was teaching at the University of Wisconsin.
So he was probably a little bit biased.
So we'll hear a little more about Chamberlin as we go along,
but I want to start just so you have an image
of what it looked like to have the glacier here
about 30,000 years ago.
You're going to see a little movie now
that will show the glacier coming down
fairly rapidly about 30,000 years ago
and then staying out pretty much near its outer edge
until about 18,000 years ago.
And that's when climate warmed,
and the glacier really started to edge,
started to fluctuate in its position.
So it retreated and advanced and it retreated and advanced.
And that's probably when most of our glacial features
in Wisconsin formed.
It was pretty late.
So from about 18,000 years ago
until the glacier left Wisconsin about 10,000 years ago
is when most of our landforms,
like drumlins and so on, formed.
So watch the movie.
31,000, 30,000, 29,500 and so on.
And, of course, you know that
these are the Madison lakes down here.
And sometimes a lake forms out here.
That's called Glacial Lake Wisconsin.
You'll hear a little more about that as we go along today.
And Glacial Lake Baraboo.
But you see the glacier is staying more or less
out near its outer edge.
And now, 18,000 years ago,
now things start to happen quickly,
and it goes way back up in the Lake Superior Basin,
advances back down, way back.
And so probably that's when a lot of our landforms
here in Wisconsin were forming.
Whoops.
So, I want to talk a little bit about
how a glacial geologist explores the landscape
and interprets the landscape.
And one of those ways is by mapping what's on the ground.
And the first map that we had of glacial deposits
in southern Wisconsin was done by TC Chamberlin.
He was at the university,
eventually became president of the university,
and Chamberlin Hall on campus
is named after him and so on.
But then he moved on to Beloit College
and to the University of Chicago.
But he was also head of the US Geological Survey
mapping division that covered glacial deposits.
So he produced this map,
and I think you can recognize just from the shape
of the lake here, this is Lake Mendota.
The edge of the glaciation he recognized
was out here through Cross Plains.
But otherwise it's a pretty simple map.
He didn't have much to deal with because he had no images.
He had no air photos.
He didn't even have topographic maps.
So this was all done basically by
riding around on horseback looking at things.
And so this was, again, that was from about 1880.
This one is from about 1892.
And you can see there's really not much more detail.
Maybe a little better shape in the lakes,
but this basically derived from the same thing
that Chamberlin had.
And the first breakthrough
was the development of topographic maps.
So the first topographic maps in this area are about 1890,
and then people actually had contours
and they could see the shape of the landscape.
This was done primarily by hand surveying.
This was not, we didn't have air photos then.
So it was a little bit crude, a little bit generalized,
nothing like the detail we have today, but, nonetheless,
it was just a huge step forward.
And there were two additions
of the Madison quadrangle 1890 and 1892, basically the same.
They tweaked it a little bit.
But the big advance was into 1904.
And this had much more intensive fieldwork,
and I think you can see that there's much more detail
in the contours than there was in those last two maps.
And that's just because there was enough time
in between those that there was a lot more ground
surveying being done.
Again, no air photos.
But this was letting someone who wanted to interpret
the landforms in southern Wisconsin
use the topographic maps to do that.
And the next major step
was the mapping that was done by William C. Alden.
He worked for the US Geological Survey.
He spent a long time in southern Wisconsin,
from the late 1890s until this was published in 1918.
So he was almost 20 years.
At first traveling by horseback, and then,
once the automobile started to become common,
he was driving around in an automobile
and did a remarkable amount of walking so that he is,
if you read his professional paper,
this is the cover of it, it is several hundred pages thick,
there's lots of things.
"Well, I stopped by so-and-so's farm,
"and he told me that he had a well that's 60 feet deep
"and it had wood at the bottom."
Or these kinds of other, so he was obviously
really connected to the people that were living
on the land here and getting a lot of his information
about what was in their well and so on firsthand.
This is the map, one of the maps that he produced,
but these are the glacial deposits.
And here's Lake Winnebago up here, Horicon Marsh,
there's the Madison lakes,
and the pink here is glacial till.
That is material deposited directly by the glacier.
And then the yellow is sand and gravel
deposited by streams flowing away from the ice.
And it's a remarkably detailed map.
I mean, this person spent a lot, lot of time
on the ground walking, driving slowly,
or riding his horse to do this kind of mapping
and digging a lot of holes.
So it's really good, and it's almost something
that's hard to beat even today.
That's just a blowup of it to show you the kind of detail.
The dark things here are the drumlins.
You can see them spreading out here from up by Beaver Dam,
coming down by Madison.
And, again, that's the Madison lakes.
And then the outermost moraines here were named by,
had already been named by Chamberlin.
This is called the Johnstown moraine,
and the moraine behind it is the Milton moraine.
And those are just ridges built out near the edge
of the glacier as the glacier carries debris
down and then drops it as the ice melts.
So, then we went from 1904 to 1959
before there was a new edition of the topographic map.
And by this time, of course, there were air photos.
And so this is the first map, topo map,
that was produced by air photo interpretation
and using what's called photogrammetry
to put the contours on instead of surveying in the field.
So it is more accurate, and, basically,
it's the same contour interval, but it's got more detail
and is almost certainly more accurate.
Each of these I'm showing is of the same area,
over here near the town of Windsor,
just so you can see the change
in the detail of the map as it goes along.
Well, the first air photos were in 1937-1938.
And that's a black and white set of photos
that's available online.
If you ever want to look at it, you can go on the website
for the Robinson Map Library on campus.
You go on the UW website and then the Robinson Map Library.
And then you can download these early air photos,
the black and white.
But nonetheless, this all of a sudden
let people actually see from above what was on the ground.
And that was a dramatic change in interpreting,
being able to interpret.
And it was a dramatic change in being able to draw
topographic maps because now
they could use those air photos,
especially ones that were taken a little bit later,
to put together more detailed maps.
So the scale of the map changed.
This is, I forget when this was.
This was about 1960, I think, or '62.
And this is what's called
a seven-and-a-half-minute quadrangle
or a seven-and-a-half-minute quadrangle or 1:24,000 scale.
So it's more detailed than the previous maps.
At about the same time,
images on a completely different scale became available.
These are called Landsat images.
These are satellite images.
So those allowed views of the bigger areas of landscape.
You couldn't see the detail,
but it allowed you to look at different wavelengths of light
that were being reflected and do interpretation from that.
And some things really stand out.
I mean, this is Military Ridge going out toward the west,
toward Dodgeville and farther west.
And then the next advance,
the next step, was to get digital images.
So, these are taking, basically, the topography,
but instead of using contour lines,
it's now a digital image.
In other words, there's a whole bunch of points there
that are tied with a coordinate of X, Y, and Z,
meaning elevation.
And this one is available for the whole state.
It's not using this new technique of LiDAR.
It's basically based on interpretation of air photos
done mechanically, not by an individual
actually looking at the photo and making interpretation.
And I should mention,
you'll see this red thing on several of the maps.
That's the Ice Age Trail.
It just happens to be on a lot of my images.
This is a glacial map that we put together
in the late 1970s, and it shows the Johnstown moraine here,
the Milton moraine, a little bit more detail than Alden had,
but because we had the seven-and-a-half-minute quadrangle,
so we had a little more detail.
Especially things like this expanded lake that was in here
when the glacier left, called Glacial Lake Yahara.
And with the topographic maps available at that time,
you could do fairly detailed mapping
of where that lake would have been.
On the ground, you don't see the shorelines
of this lake in very many places.
You do up in Cherokee Marsh, you do over in the Arboretum,
and you do along here on,
I'm sorry, down here off the Beltline.
So there are a few places where you can see the shoreline.
But, basically, there was one big lake here
all the way down to Stoughton and out to Middleton
and up into Cherokee Marsh,
and Alden did not portray that very well
because he didn't have the elevation control.
And we've probably got a few more drumlins and so on.
But nonetheless, that's sort of the level of mapping
that you could do at that time.
- [Woman] For those of us who have forgotten,
could you define a drumlin?
- Okay, yeah, you'll see some coming up here.
But they're elongate hills
that are produced at the bottom of the glacier.
And, basically, the glacier moves along and shapes
the ground surface into those streamline shapes.
And so those are the drumlins,
and we'll see some more details of those.
So if we try to zoom in on that image
that's produced basically from air photography,
you see it gets kind of blurry.
What I'm interested in seeing here are there's some channels
that were built along the edge of the glacier.
This is up off Highway 12, off Ballweg Road,
north of Springfield Corners.
So that's what you see,
and then if we add this new technique, LiDAR,
this is what you see.
Look at the difference.
I mean, all of a sudden we've just got a whole new scale
of viewing the landscape that we didn't have before.
And these are what are called ice marginal channels.
That is the edge of the glacier sat here,
and water came off the ice
and moved first through this channel,
it was actually probably first through this channel,
then this channel, then this channel,
and then you can see there are a few smaller ones down here.
These are some forming in Alaska.
So here's the edge of the glacier, this is the ice out here,
and you see these channels.
There's one here, one here, one here,
and there's probably one forming right here.
The water is probably forming,
running along the edge of the glacier.
And then, in the next slide, you'll see a photo taken
a year after, or maybe it was two years after,
and you'll see the ice has retreated,
and there are more channels.
Yeah.
In the last photo, the ice edge was up here,
and now it's gone back to here.
Ice marginal channels are hard to see,
and I didn't realize those were there
when I looked at the air photos.
This is what you see on the air photo.
That's where the channels are.
Even with what are called stereo pairs,
looking at two together so you get some 3D,
you just don't see them.
Vegetation blocks them and so on.
But LiDAR has the advantage
of looking through the vegetation.
So, you can actually,
well, you can adjust it different ways.
You can have it look at the vegetation
or you can have it remove the vegetation
and look at the actual ground surface.
And that's such a huge, huge advantage,
especially in a forested area because with air photos
you don't see much in a forested area of the details.
So, how is it done?
Well, the data are collected,
and I'm no expert at this at all.
I mean, all I do is interpret the images.
I don't get involved in dealing with the data.
But this is airborne, and it uses a combination of radar
plus some light sensing device as well.
And you get, basically, digital images
that are just a scatter of data points,
and they can be then, this has vegetation on it
and you can remove the vegetation and you can refine it.
And that's all I'll say about that
because that's all I really know about that.
But it gives us a terrific advantage
in looking at these glacial fixtures.
Just to give you an idea of the status in Wisconsin,
unfortunately the many surrounding states,
the whole state just did it,
but in Wisconsin the state chose not to do it
and they had individual counties go off
and try to raise the money to do it.
So the better off counties down here
in southern Wisconsin have it,
and all the green ones here are available
to the general public.
You can just go on the website and get it,
if you have the right software to look at it.
And then the rest of these, some of the counties,
the colored counties have done it themselves
or paid for it themselves, and then some counties just,
I think, have decided they don't have enough money to do it.
So it's not getting done, and it's really unfortunate
because this is such a good source of information.
So, we come back to the kind of map
I could make back in the 1970s,
and obviously seeing that kind of detail
you could make a much better map.
And I don't know if I ever will,
but I just want to now we'll run through some examples
of landforms and the kinds of things
that you can see or can't see on them.
So, this is a topo map just out southwest of Madison.
The extension of Mineral Point Road
is just off the map here.
Tumbledown Trail is just south.
It's a golf course here.
And, if you look at it, you can say,
well, there must be something kind of funny here
because there's more forested ground,
but otherwise it really isn't apparent where the moraine is.
But that's the outermost moraine.
That's where the Johnstown moraine is.
But, gee, where is it?
If you look carefully, you can see it way out here.
It's actually here.
It's a little bit of a ridge here and so on.
But even looking at the landscape here versus here,
it's hard to see a difference, isn't it?
And people are always saying,
"Well, how can you tell when you drive west from Madison
"where you go outside the glaciated area
"into the driftless area?
"The area that wasn't glaciated?"
Well, it's hard to do unless you know where it is.
But then when you look at the LiDAR,
look at the, now I'll tell you where the moraine is.
The moraine goes right up here, but can you see the difference
between that landscape and that?
Look at the dramatic difference.
You can't see that on the topographic map.
Again, this is a tool that shows things
that we just couldn't see before.
You couldn't see it on the air photo,
you can't see it on the topo map,
but it stands out nicely in the radar.
So, it's a real, it's a real boon to those of us
who are interested in making maps
and understanding where different glacial deposits are.
I'll give you another example.
So, this is the glacial map on the west side of Madison.
This is Black Earth Creek going down here.
So Cross Plains is right here.
And along here you can actually trace
the moraine fairly well.
Some of you have probably driven out Mineral Point Road,
and you've see Shoveler's Sink.
That's where the Shoveler's Sinks are,
and that's the outermost moraine.
It's a considerable ridge there.
So it's pretty obvious there.
And you can trace it up this way.
But then you kind of lose it, and then up here,
there basically is no moraine
that shows up on a topographic map or that you can see.
So when we mapped this back in the '70s,
we went back and forth and tried to see
where there were rocks that had been carried by the glacier.
Glaciers carry some rocks from a long distance away.
They're called erratics.
And so in the driftless area that wasn't glaciated,
there are no erratics.
So at least by following sort of the distribution
of erratic boulders, we drew this line in.
But now when we look at it, oh, sorry.
So there's the topographic map.
That's, again, that's the table bluff segment
of the Ice Age Trail.
You look at this though,
and basically it's bedrock topography.
You can't see where the edge of the glacier was from there.
But if we go to the LiDAR,
here's that same table bluff segment of the Ice Age Trail,
and now I'll tell you here's the moraine.
It's coming up here.
You see that. It goes this way.
Look at the difference in the landscape here
versus the glaciated.
It's just so distinct. It's amazing.
And to think of the days that we spent back and forth
trying to figure out where the heck the glacier stopped.
Well, this actually does come up here.
There's a small ridge here. It follows up.
You can see things that are just amazing that,
that we just couldn't see before.
So it's a dramatic change in what you can see.
Another example, let's look at some features
that formed back under the glacier.
One of these is called a drumlin.
These are these elongate hills
that formed beneath the glacier.
And here's one from the air.
Oftentimes they're not symmetrical.
They're often steeper on the up-glacier side
than the down-glacier side.
So the glacier is flowing from left to right here.
And here's a nice, long one up by Beaver Dam.
Some are more short and stubby,
like this one out just off the Interstate 94
between here and Milwaukee.
And here they are in northern Dane County using the LiDAR.
This is Highway 151.
Columbus is just off the map to the upper right here,
and Sun Prairie is down here.
This is the county line with Columbia County.
And you can see that these features really show up.
Not only the big hills but you're seeing in between
these smaller grooves.
So we're going to look, zoom in now on this site up here.
That's a farm building right there.
And we're going to zoom in on this.
You can see, I put this in so you can see
this is what we mapped in the '70s.
Well, we just made it all green
because we couldn't see any detail.
The topographic map, again,
that house that you're going to see in a minute is here.
What do you see? Not much.
What do you see on an air photo?
Here's that farm buildings again.
Notice that now in the air photo
you do pick up some finer lineation in the landscape.
And notice also on the air photo this field
because that's going to show up in the next image.
Okay, we go to that broad DEM.
Nothing at that scale.
But look at the LiDAR image.
Here's that same farmhouse building,
and the glacier obviously is flowing from
upper right to lower left.
This is a recognizable drumlin,
but look at the fine detail in between.
The whole surface here is lineated
that you couldn't see before.
You couldn't even see them on air photos.
And what's amazing is look at, here's a fence line.
That's an artificial drainage ditch.
Here's the fence line.
This field has been plowed going north to south.
And you can see that the lineation here
is basically the same scale as the farmer's furrows.
I mean, it's just amazing the detail that you can see there.
That plowing here has erased that fine grained detail.
So, you're really getting in to look at what's reflecting
what was happening at the bottom of the glacier.
I mean, presumably each one of these little grooves here
represents a boulder stuck on the bottom of the glacier
that's being dragged along and making a groove on the bed.
So we're looking at the pass of individual boulders
at the bottom of the glacier.
So I think that's just really dramatic.
It's something that you can't even see it
when you stand there.
I mean, you cannot see that pattern without this.
Let's skip around now and go look at a few more features
in the next 10 minutes or so.
We'll first look at what the terraces
and the floodplain look like out here by Mazomanie
on the Wisconsin River Valley.
This is what the LiDAR image looks like.
So just, again, to get you located.
So here's Mazo, and you'll see this point of land.
We're looking at about, well, actually, on the first slide
we're looking at this whole area.
Okay? Out to Spring Green.
So Spring Green is just off the map here,
and Mazomanie here, and what you're seeing are terraces
in the Wisconsin River Valley.
Terraces are old stream bed surfaces
that have been abandoned as the river has cut down.
So, when the glacier was out at its maximum position,
a wide stream carrying sand and gravel
was flowing up at this level.
And then as the glacier pull back,
the stream tended to cut down,
and the Wisconsin River has two major terrace levels,
this one and then a lower one.
And then there's actually kind of an intermediate area
that doesn't look like it has recent coverage of the stream,
and then we have the modern floodplain
that gets flooded pretty regularly when they're high flows,
when there's lots of water.
So we're going to zoom in and look at a few other features.
Notice these fun, squiggly features out here.
We'll see those.
Those are sand dunes.
There were sand dunes out here.
When the glacier was here,
that was bare ground blowing sand across that surface
and probably for some time after,
and some of these probably even got reinvigorated
during the very dry times of the 1930s.
But there are nicely developed sand dunes out there.
You can see some cultural features.
See those houses in Mazomanie, or in Arena.
That's Arena.
Then you can see, look at the difference.
Here's clearly the floodplain.
Those are the channels that get occupied
when the water is high.
But most of those features that had been up
on the terrace here, those are erased by farming and so on.
But they were there.
That just zooms in to the sand dunes a little bit more.
Again, the channels on the floodplain
versus the sand dunes and then high terrace
that the channels have basically been erased,
the old channels that were there.
More detail right down on the floodplain now.
This is called a braided stream
because these channels basically form a braid across,
and they occur when rivers have lots of sediment
at the bottom, in the bed, that's being carried.
All right, we're getting close.
Another feature that's kind of neat to see
forms in tunnels like this underneath the glacier.
They're called eskers.
And so here's a tunnel, and sediment,
sand and gravel gets deposited in the tunnel,
partly fills it, and then when the glacier is gone,
it leaves behind a ridge.
And these really show up nicely.
This is one over in Jefferson, eastern Jefferson County,
I think, or Waukesha County.
Here's another one.
Some of these show, the bigger ones show up on topo maps,
but the small ones don't.
The small ones you have to have that
kind of level of detail to see.
Another thing that happened
along the edge of the glacier was glacial lakes.
It was common for water to be dammed in those.
And oftentimes there were deltas farmed
along the edge of the glacier.
And we see really good evidence of that in several places.
Now there was a big lake here that went basically
from Dane County to Waukesha County
called Lake Scuppernong.
And there are a number of places along the edge
where we can, with this, see deltas.
So here is a, this is a delta.
This was built out into the lake.
This is deeper water lake sediment.
And this is the edge where the ice sat.
So the glacier sat along that steep edge, water came off,
and sediment was being deposited
out into the lake in that delta.
Well, that just doesn't show up on a topographic map.
It's just too low relief to see.
Another big lake we had was Glacial Lake Wisconsin.
To get you oriented, this is Wisconsin Dells,
this is Mauston, the M here,
and this big lake drained whenever the glacier
got east of the Baraboo Hills here near Portage.
And so we had this big lake basin,
and we now have the present day Lake Wisconsin, sorry,
Wisconsin River flowing across it,
as well as some tributary streams.
And we'll just zoom in on those a little bit.
So here's the former bed of Lake Wisconsin.
It has some sandstone bluffs sticking up.
That's Quincy Bluff.
That's Mauston, New Lisbon, I-94, and there's two,
so we got the major one, which is the Wisconsin River.
That has lots of coarse sediment in it,
and so it's a braided stream still.
It has these elongate islands going through it.
The Lemonweir River, which comes into it,
has a very low gradient.
It has a low gradient because
the whole Wisconsin River Valley
is higher flowing on this lake sediment
than it was before the Glacial Lake Wisconsin was there.
And so let's look at the closeups of these now.
Oh, sorry, I was going to,
there were sand dunes there on the
bed of Glacial Lake Wisconsin too.
Those are sand dunes.
Here's what the Wisconsin River Valley looks like.
And you see these elongate islands.
Those are typical of braided streams.
They have lots of bed load,
lots of sediment at the bottom, either sand or gravel.
But look at that. How different.
This is called a meandering stream,
and this is sort of extreme meandering
because the river is trying to take its time going downhill
because it otherwise would be, it would,
well, it's not the river doing it, obviously.
It doesn't think about it.
It's just what's demanded
by the flat landscape it's going over.
And so these things migrate and they cut,
have cut banks on the outside of the meanders
and point bars in the middle,
and these things move back and forth.
And there's been considerable study
getting radiocarbon dates on these.
In fact, a student in geography a few years ago
did her PhD on this stream system itself.
So, that basically brings us to the end
of the presentation, and what I want to do
is just find the, give you some of these sources,
if you want to look at them.
The USGS has all topographic maps
they've ever made available online.
So you can just go on there and you can download them
as PDFs all the way back to the 1800s.
The LiDAR images and the newer air photos from Wisconsin
are available from this Wisconsin View Map Portal,
and that's the website.
So I think if you just Googled Wisconsin View Map Portal
or Wisconsin View.
But they have 2008, 2010, 2012 color air photos
of the whole state.
So you can download those.
To get these LiDAR images that I'm looking at,
you need to have a program that can open them
and make a shaded relief.
So that means a GIS program.
ArcMap or something like that.
And then the 1937-1938 air photos
are all online at the Madison Robinson Map Library
at that website.
And again, you can just download them.
So if you're interested, you live out in the country
and you want to see what it looked like in the '30s,
that's the place to go and do it.
Okay, so, thank you.
(audience applauding)