- The local rocks, the Dolostone,
tend to be bigger and blocker.
I do love rocks.
They have mysteries to share with us.
And I don't think
we'll ever get down to the bottom of all of them.
We're in the Lawrence University Geology Department.
So everybody good?
We put a big emphasis on field-based learning.
And then all of a sudden,
we have this hill that's very well drained.
It's kind of dry-looking.
It has much sparser vegetation on it.
? ?
So this is where students
who have generally no background in geology
may first encounter what I call geologic logic.
This thing's at least 15 meters high,
which would put it at around 50 feet high.
We try to instill in students
a curiosity about what these rocks signify.
- I think the glacier sedimented all this stuff here
from other places.
- They're not just inert objects.
They're records of events that affected this part of the world
as well as the entire globe.
What kind of sediment did you encounter?
- Sand.
- Ok, there's definitely sand.
These are all observations that will constrain our hypotheses
about what formed this thing.
I can't help myself.
It's just an intrinsically interesting thing
to be able to look at a landscape
and read what happened in the past.
It seems like a wild hypothesis;
a deposit left by a sub-glacial river.
But it is almost the only way to explain all the observations.
Congratulations, you did figure it out
and the name of this feature is an esker.
Most of the people, including myself,
who do end up in geology are kind of accidental geologists.
They found it taking a required science credit
and stuck with it.
? ?
I had grown up interested in landscapes
and spending a lot of time outdoors.
I did grow up in western Wisconsin,
in an area where Cambrian Sandstones were exposed.
I do remember
going out with my father looking for trilobite fossils.
Every day I'm grateful that I found my way into this field
because it does have such explanatory power.
Suddenly it was like learning the etymology of a word.
It was here's the etymology of landscapes around us.
We're up here on Cactus Rock.
I would guess this is about red granite age,
so that would put it at about 1.75 billion years old,
the rock itself.
This was either a high on the bottom of the sea floor
or possibly even an island
at the time that the Cambrian Seas came in.
There are so many distinct chapters.
There's the original formation of the rock.
And then it's probable burial during the time
when we had marine sedimentation.
Then it's unburial.
Even before the Ice Age,
it was probably being exhumed by rivers
and other forces of erosion.
We can also see evidence that the glaciers were here
just the other day.
And I can feel how incredibly smooth this is.
The glaciers scoured off the landscape of Wisconsin.
These crescentic fractures too are records of glaciation.
They're called chatter marks.
This is a classic, glaciated outcrop in Wisconsin.
Any place has that sort of story
if you just look a little deeper.
All parts of Wisconsin
have interesting and different stories.
The northern third of the state or so are the oldest rocks
ranging in age from about a billion years old
all the way back to about 2.8 billion.
We can see the guts of these ancient mountain belts
and volcanoes.
We have in fact
a longer record of geologic time here in Wisconsin
than all of the Grand Canyon.
The rocks in the bottom of the Grand Canyon
are relatively young
compared with the oldest rocks in Wisconsin.
These are ripple marks
that formed when the sand was being laid down.
I'm interacting with ancient waters
that flowed over these sediments before they became rock.
We can tell even the direction of water flow.
It does take an active imagination.
I think that's something interesting about geology
is that it takes spatial visualization
and it takes a certain capacity for imaginative thinking
to think back to a time
when the landscape was utterly different
and yet it's tangibly still with us.
You see how high this is.
Imagine how much ice was over us
to be a tunnel underneath a significant amount of ice.
Geology is such an amazing lens through which to see the world.
Wherever you are,
there's something geological under your feet.
It's reminding us that landscapes are ephemeral.
They come and they go.
That there have been other versions of this place
and the globe,
but we are also part of this immensely long story.
So it doesn't diminish us.
It should enhance our sense of wonder
and connection to the natural world.
? ?