Name:
Geology 310
Professor Moosavi
Purpose:
Our goal for today’s field trip is to pose some big questions to provide a framework for the course. Contained below is an itinerary with activities and questions for the locations we will visit. Your observations and thoughts should be recorded within your classroom journal. Remember to leave some blank space to add to your answers later on.
The BIG QUESTIONS! (Like those your students may ask!)
What was Minnesota like, long,
long ago?
What makes life possible here on
the earth?
What determines the ecosystem
found in a place?
How will the land change in the
future?
What role do humans play in that
future?
Stop
1 MSU – Mankato
Trafton Lawn
What can we learn about the geology of
Minnesota in this spot?
Why?
· Brief discussion.
Where could we go to learn more about
Minnesota’s geologic past?
· EN ROUTE: Note the landscape features we traverse.
(Gage Hill, Stoltzmann Road Wetlands,
Mt. Kato)
What could account for the landscape
features we see?
Stop
2 Blue Earth River
MN Rte. 66 and Blue Earth County Road 90,
Park in small roadside lot.
· Hike along trail at woodland, field
boundary.
· Upon entering the woods, look for features
of the valley present.
· Note the small lake along the trail and
stop.
What material appears to underlie this
site?
· Feel free to use the spade to dig a small
sample.
What
can you conclude about the underlying material?
· Continue walking until you come to the
river.
· Look into the river.
· Describe the quality of the river water
in terms of its color and turbidity.
· One student should take a sample of river
water for return to the lab.
(We’ll compare this with another sample after it has settled to
look at turbidity.)
Is
there life within the river? What
kind?
What
is the bottom of the river like?
Does
erosion or deposition appear to be occurring here? How do you know?
What
do you notice about the forest floor? (Is something missing? Does it look like
a typical forest floor or has something happened to it?)
What
process could account for the state of the forest floor?
· Examine the raised structure along the
riverbank.
What
could account for this structure?
How
might it form?
· Draw a quick side profile of the valley
from the river into the forest. Focus on elevation, structure and location of
vegetation.
What type of vegetation is present
here?
What characteristics must this
vegetation have to survive here?
How would this site change if the vegetation
were removed in terms of its stability?
· Continue walking along the river trail
until it plunges into the water.
What is occurring with the river in
this location?
What evidence might you find elsewhere
nearby to support your contention?
· Brief discussion before walking back to
the van.
What do you call the landscape we just
visited?
Stop
3 Red Jacket Bridge
MN Rte 66
· At this site we will look at the stream
gauging station below the bridge before ascending the steps to the Red Jacket
Trail.
What
is the importance of measuring stream discharge?
· Make a sketch on how you think a stream
gauge might work.
· After climbing to the bridge, take a good
look up and down the valley of the Le Seuer River.
What is the shape of the river valley
here?
· Make a quick sketch of the river
valley’s shape.
What
do you observe is occurring downstream from this site (think of Stop 2!)?
What
features that you have observed so far today might this explain? How?
What
3 major economic activities have you observed in this valley?
How
does the geology present dictate these economic opportunities in each place?
What
do they tell us about the geology in turn?
· Brief discussion before returning to the
van.
Stop
4 Road Cut
MN Rte. 66 near hilltop.
· Look at the material exposed by the road
cut.
· Describe the texture and composition of
the material.
· Note the large boulder seen at the upper
right.
· Consider our elevation near the top of
the river valley.
What
is this material?
How
did it get to be in this location?
How
old do you believe it is?
What
role does this material play in soil formation?
What
role does it play in aiding/impeding our ability to examine the underlying
geology?
· Look at the shape of the side valley
across the road from the road cut.
· Draw its shape.
What does this tell us about the age
of this small valley?
What stage in stream development are
we seeing?
Stop
5 Agricultural Land
Along Blue Earth County Road 9, East of
Rapidan
· Look to the south of County Road 9.
Describe the nature of the landscape that you see.
What
do you believe created this landscape?
When
would it have formed?
If
you were to dig down 3 meters in that area, what would you expect to encounter?
Stop
6 Rapidan Dam
Blue Earth County Road 9, 2 miles West of
Rapidan
· As we approach Rapidan Dam note the shape
of the Blue Earth River Valley we are entering.
· Next, examine the dam itself.
What does the dam appear to be used for?
· On the dam, first look downstream.
· Describe the shape of this part of the
valley.
How is this valley’s shape the
same or different from the part of the valley above?
Why?
What is exposed below the eastern end
of the dam?
Is this material the same or different
from that at Site 4? How?
What type of rock do you believe this
is? Why? Be as specific as you
can.
Where might we go to examine these
rocks close up?
· Describe the bed of the river below the
dam.
Is this bed similar to that seen at
Stop 2? How or how not?
· Next look upstream of the dam (south).
· Describe the environment you find
there. Note the vegetation and
foam in the water especially.
Where does the river water appear to
be moving more energetically, above or below the dam?
What effect might this have on the
river’s sediment load?
What is the cause of the foam?
What effect might this have on
chemical contaminants contained in the water?
How has the presence of the dam
altered the river valley in terms of its geology?
Where are erosion and deposition
occurring?
How has the presence of the dam altered
the river water in terms of its turbidity?
How has the dam altered the conditions
for life in the river (temperature, nutrient status, oxygen level, migration
routes for fish, etc.)?
What is the ultimate fate of this
system?
Once this occurs, what would you
predict would happen if the dam were removed? Think in terms of erosion, deposition, and water quality.
In light of all you have said, is the
presence of this dam benign, i.e. does it produce the benefits it is intended
to without negative impacts?
What does this tell us about this form
of meeting this societal need?
· More extensive discussion before leaving
by van.
Stop
7 Mills Lake
Off
US 169 South of Blue Earth County Road 9.
· Examine the shoreline and water of Mills
Lake.
· One student should collect a water sample
for return to the lab.
· Another student should measure water
clarity using the Secchi disk from the end of the dock.
Where
does water for this lake come from?
Where
does it go? (Describe 3 possible exits.)
How
did this lake form?
How
is it likely to evolve in the future?
What makes the water of Mills Lake so
turbid?
What
does that tell us about the water quality?
What
role does the farmland around the lake play in its water quality?
What
role do the trees along the shore play?
How
is this lake likely to evolve over the next few thousand years?
Stop
8 Tributary Stream
Judson Bottom Road
· Begin by examining the pinkish/purple
rocks along the road embankment.
These rocks are not native to this site, but were brought in from an
hour to the West.
· Use the rock hammer, HCl acid, your
knowledge of rock identification to classify the rock in terms of general and
specific type.
What
general and specific type of rock is this?
How
does the acid test help you to distinguish this rock type?
What
mineral does this suggest is found in this rock?
What
would give the rock this interesting color? (Is it a Vikings tribute?)
What
environment would this rock have formed in originally?
Why
would MN DOT spend so much money to bring in this rock for road stabilization
instead of using local rock?
· Next, enter the small stream valley from
the opposite side of the bridge.
· Describe the shape of the valley.
· Look at the rocks in the outcrop across
the stream above you.
What
do these rocks appear to be made of?
What
general and specific types of rock are they?
Are
they strong or weak?
What
geologic process are they undergoing?
· Look at the rocks in the streambed and in
places along the bank. Look at how they break.
Are
these rocks of the same type as the others?
What
do they appear to be made of?
· Use the rock hammer, acid, and your
knowledge of geology to identify these rocks.
What
mineral are they made of?
In
what environment would they have been deposited?
Does
the presence of these rocks play a role in determining the shape of the
valley? If so, what?
What
would happen if the stream were to erode through this layer of rock?
How
old is this small valley?
How
did it come to be?
How
old are the rocks in this small valley?
· Before leaving the valley, look around
the base for any rock that does not match the 3 types we have just looked
at. Bring it to the attention of
the class.
What does the rock appear to be made
of?
What does its shape tell you about it?
Does it appear to belong here?
If not, where did it come from?
How did it get here?
· Discussion before returning to the van.
EN
ROUTE: Note the rock beds exposed
along the highway.
Focus on their levelness and
structure.
Stop
9 Minnewaukon Falls
Judson Bottom Road
· Be careful at this site as we are along the
road. Examine the stream from the highway
bridge. Look both up and down
stream. This is the same rock bed that supported the stream at stop 9. Here however, the rock bed has been
breached by the stream. Look at
the results.
What
happens to the stream as it heads toward the Minnesota River?
What
feature do you expect to see there?
· Walk around to the fence and look back at
the stream.
· Draw a quick sketch of what you see.
What is the shape of this stream
valley in profile?
What is happening at this location?
What role do the rock beds exposed
play in creation of this feature?
Is this feature stable? If not, how
has it and will it evolve over time?
How old is this feature?
· Brief discussion before returning to the
van.
Stop
10 Road Cut
Judson Bottom Road
· Begin by looking at the bed of the small
stream along the road.
What
is the shape of this stream valley?
Why
is it different?
What
effect is this having on the course of the stream?
· Look closely at the bends in the stream.
What
are they called and how do they form?
· Sketch one of the bends. Indicate where you think the water is
moving fastest and where it is moving slowest.
What effect should variable speeds
have on the stream’s ability to do work?
How will this manifest itself in the development
of the stream channel?
· Indicate on your sketch areas of erosion
and deposition which result.
How
is this small stream likely to evolve in the future?
Would you build your house across this
stream from the road? Why or why
not?
· Move on to the rock outcrop to the right.
Look closely at the layers in the rock.
What 2 types of rock are we seeing?
· Use the acid test on samples that have
fallen from the cliff to verify your identification.
Why does the darker layer overhang the
lower layers?
What would this form in a wetter
setting?
· Test the hardness on a sample of the
white rock.
How strong does the white rock appear
to be?
· Look at the layers within the white rock.
They layers cross back and forth.
· Speculate as to the cause of these cross
beds.
What do they suggest about the
environment in which they formed?
· Brief discussion before returning to van.
En
Route: Look at the structure of the
Minnesota River and its valley to our right.
Look for its resemblance to other features
seen on this field trip.
Look also at the rock outcrops on our
left. See any parallels?
Stop
11 Look Out Drive Overlook
Look Out Drive, North Mankato
· Look up and down the Minnesota River
Valley.
· Describe its shape.
· Look at the industries and towns present.
· Look at the notches in the opposite
valley wall.
Why is the Minnesota River valley so
big compared to the river?
Did the Minnesota River form this
valley? If no, how did it form?
How did the notches in the valley wall
form?
What would you expect to find in each
case?
How old is the Minnesota River valley?
Why is the valley not deeper than it
is?
Why does the river valley make such a
sudden sharp bend north of Mankato?
What does the river appear to be doing
when it bends back in forth?
Why does this happen?
What does this tell us about the scalability
of geologic processes like stream channel evolution?
What materials would you expect to
find underneath the river?
How would you expect this river valley
to evolve over time?
What would happen if very heavy rains
and snowmelt were to occur upstream?
How has the presence of the river
valley affected human occupation of this area?
· Final Discussion before returning to MSU.