Exercise on the Lake Michigan Shoreline -
Virtual Flight along the Eastern Lake Michigan Shoreline
What follows is an exercise involving a virtual flight along a portion of the
eastern shore of Lake
Michigan from south of Saugatuck to Muskegon
(Map 1). Topographic maps accompany many of the
photographs so the locations that those photos were taken can be determined by
carefully comparing the photos to the maps. The contour interval for each
map is 10 feet. In cases in which the students need a scale to answer a
question, they can locate the scale by scrolling down to the bottom of the
map. The students also may need to scroll around on the maps in order to
find the location of interest. Although this exercise can best be used
after the students have had a brief introduction to topographic maps, some
parts of it can be done by students who have had no experience with topographic
maps. To aid in selecting only some portions of the exercise to make as
an assignment, the sections of the exercise have been numbered.
Virtual Flight along the Eastern Lake Michigan
1. Our flight on April 22,
2000, aboard a Cessna 172 (Photo 1)
begins at the Riverview Airport
in Jenison, Michigan
(Map 1). The elevation at the airport, as noted
on the hanger, is 603 feet above sea level (Photo 2).
Once we are in the air we soon see gravel pits (Photo 3
and photo 4). On Map 2
locate the gravel pits just south of the Grand River.
At about what elevation are the gravel pits located? Most gravel and
sand-mining operations in Michigan
are in glacial outwash, which is sediment deposited by meltwater
streams associated with a glacier. Why might deposits of outwash form
better sources of sand and gravel than till, sediment deposited directly by a
glacier? Nearby we see houses built around lakes located in former gravel
pits (Photo 5). This is a good example of a
secondary use of land following a mining operation.
2. As we fly southwest toward Holland,
we fly along the Zeeland Channel (Photo 6 and Photo 7). This Channel marks the location of one
of the two channels that formed the Grand River during
glacial times. After the Zeeland Channel was abandoned over 12,000 years
ago, only the Grand Haven Channel of the Grand River
remained with its mouth at Grand Haven to the north (Map 1).
Locate the Zeeland Channel on Map 3.
Describe how you were able to locate the Channel on the map. (Hint:
Describe the distance between contours on the floor versus along the sides of
the Channel.) What is the approximate maximum difference in elevation
between the floor of the Zeeland Channel and the higher land immediately to the
south? How wide is the channel? Based on the dimensions of the channel,
what words would you use to describe the size of the channel? To see the Zeeland
Channel in 3D go to 3D Map 1. In the view shown
by the map, we are looking west, toward Lake Michigan.
The vertical exaggeration is 8X, which means the relief shown by the map is 8
times what it actually is.
3. We finally reach the Lake Michigan
shoreline! We first view the shoreline south of the towns of Saugatuck
and Douglas. Study the shoreline in the southern portion of Map 4. Based on the contours, do you predict we will
see sand dunes at that location? Now study Photo 8.
You should be able to find the exact location of Photo 8 on Map
4 by carefully studying the parking lots and orchards in the photo and
comparing them to the symbols on the map northwest west of the cloverleaf on
Interstate 196. (Orchards are shown as green dots on the map.) Do
you see sand dunes in the photo? Was your prediction correct, are dunes
present? To see what the shoreline looks like in 3D go to 3D Map 2 (4X vertical exaggeration), which is a view
looking east. Now go back to the topographic map (Map
4) and find the maximum elevation that is within 2000 feet of the shoreline
at the location shown in Photo 8.. What is the
approximate elevation of the surface of Lake Michigan?
What is the maximum relief in this area (obtained by subtracting one elevation
from the other)? Based on the direction the waves approach the shoreline
(Photo 8), what is the
direction of the longshore current? (You may
wish to review "Longshore
Current and Beach Drift".) By studying the water in the photo,
can you find any evidence that sediment transport is occurring?
4. We continue our flight to the north along the shoreline. Soon
we spot Oval Beach.
Find Oval Beach on Map 5. Based on the contours,
do you predict sand dunes are found in this area? Now look at Photo 9 and 3D Map 3 (looking
east; 4X vertical exaggeration). Was your prediction correct, are sand
dunes present? On the topographic map what is the maximum elevation you
can find within 2000 feet of the shoreline? What is the maximum relief in
this area? How does it compare to the relief you calculated for the area
south of Saugatuck/Douglas? (Hint: How does 3D Map
3 compare to 3D Map 2? Also, on the
topographic maps notice how much closer together the contours are at Oval
Beach than in the area south of
Saugatuck.) How does the maximum elevation at Oval
Beach compare with the elevation
back at Riverview Airport
where our flight began?
5. As we fly on we see the mouth of the Kalamazoo
River just north of
Saugatuck/Douglas (Photo 10). Notice the
jetties that have been built on either side of the river mouth. The
jetties are meant to “jet” the water out of the river channel and keep the
channel open for navigation purposes. What is the origin of the brown
colored water (plume) directly out from the jetties? (You may wish to review
“The River Plume”.) Based on the orientation of
the plume, which way does longshore current appear to
be moving? Find the location of Photo 10 on Map 5.
Based on the geometry of the sand buildup on either side of the jetty, do you
predict that longshore current always moves in that
direction? (You may wish to review "Longshore Current and Beach Drift" and "More about Longshore Current
and Beach Drift".) Explain your reasoning.
6. As we loop back to the south a little and look to the north, we can
see Douglas and Saugatuck, the mouth of the Kalamazoo
River, and, off in the distance, Holland
(Photo 11). Using Map 1
determine about how far the channel at Holland
is from our present location (the mouth of the Kalamazoo
River). What feature(s) makes
it so easy to spot the Holland
channel from such a distance? On Map 6 locate the
jetties and breakwaters at Holland.
Which direction does littoral transport primarily move sediment in the Holland
area? Explain your reasoning.
7. In no time at all we cover the distance to Holland.
Find the precise location of Photo 12 on Map 6. (Hint: A portion of Lake
is shown and the channel going out to Lake Michigan is
in the left central portion of the photo.) On the map
find the large, parabolic dune (commonly formed by a “blowout” of previously
vegetated dunes) shown in the photo. Sketch the contours that
depict the parabolic dune. That is a typical contour pattern for
parabolic dunes. Based on the shape of the contours in your sketch, do you
predict other parabolic dunes are located along the shoreline in the vicinity
of Holland? A dune located
south of Holland is shown in Photo 13. Is this a parabolic dune? What
evidence indicates erosion has occurred? Study the 3D map (3D Map 4; looking east; 8X vertical exaggeration) of the
area bordering the channel at Holland.
Do you suspect at one time the two parabolic dunes just south of the channel
may have been a continuous dune? Explain your reasoning.
8. Study Photo 14, taken of a view we see
north of Holland. In that
photo can you find evidence that erosion has occurred? Explain.
9. As we continue our flight we see Tunnel
Park. Locate the park on Map 6. Is the elevation higher to the north of the
word “Tunnel”, or to the south? Now examine Photo
15. Were you correct? How is the water tower in the photo
depicted on the map?
10. As we fly along we continue to see evidence that erosion has occurred
along the shoreline. What evidence can you give that indicates
erosion has occurred south of Port Sheldon (Photo 16)?
11. Soon we reach Port Sheldon and see the power plant (Photo 17) there. Locate the power plant located
just to the north of Pigeon Lake
on Map 7. Why are all the power plants we observe
on our flight located along water?
12. At Little Pigeon Creek we see a spit (Photo 18).
Based on the configuration of the spit, which direction must littoral transport
be moving? (You may wish to review "More
about Longshore Current and Beach Drift".)
The plume we observe at the mouth of Little Pigeon Creek is dark colored,
probably because it contains tannic acid, which forms naturally from the decay
of organic material such as oak bark. Find Little Pigeon Creek on Map 8. (The creek mouth is highlighted in
blue.) Does the stream flow through forests (green on a topographic map)
and swampy forests (green with a light blue pattern), likely sources of such
decaying material? Explain.
13. Millions of people depend on Lake
Michigan and the other Great Lakes for
their drinking water. On Map 8 locate the water
treatment plant that we fly by and that is shown in Photo
19. (Hint: It is located at the west end of Lake
Michigan Drive.) Many people, for example
those living in Grand Rapids to the
east, use water from this plant. Name as many sources of pollution that
you can think of that result in the need to treat Lake Michigan
water before we can drink it.
14. We take a photo (Photo 20) of groins
(structures built perpendicular to the shore) as we fly along the shoreline
north of Port Sheldon. Based on the configuration of the shoreline
relative to the groins, which way does littoral transport normally move in this
area? (You may wish to review "More about Longshore Current and Beach Drift".) To
support your answer, draw a simple sketch of the groins and beach sediment.
Your sketch should be a map view, or "bird's eye view" of the
shoreline. Based on the configuration of the waves (Photo 20), which way was littoral transport moving
when we took the photo? (You may wish to review "Longshore Current and Beach
Drift" .) Again, support your answer
with a "bird's eye view" sketch of the waves and shoreline..
15. After a short time, we arrive at the Grand River Channel in Grand Haven
(Photo 21). The small harbor on the south
side of the channel is the Government Boat Pond, where Grand Valley State University’s D.J. ANGUS is usually berthed. (To
investigate going on an educational cruise on the ANGUS, go to http://www.gvsu.edu/wri/education/.)
Locate the Government Boat Pond and the power plant (to the far left in Photo 21) on Map 9. If
you were to take the ANGUS from the Boat Pond to the power plant, how far would
you have traveled in miles (to the nearest tenth of a mile)? In kilometers (to the nearest tenth of a kilometer)?
What color is the water in the Grand River Channel? Why is it that
color? We fly back over Lake Michigan and see the Grand
River plume contrasting with the blue Lake Michigan
water (Photo 22). Why is such a sharp
boundary observed between the river plume and Lake Michigan
water? Do you suspect the plume extends to the bottom of the lake?
Why or why not? In what ways do you suspect the quality of the water in
the plume differs from that in the lake? (Hint: Besides color,
think of differences you might expect in turbidity, temperature, etc.) To
help answer these questions you might review “The River
16. We fly inland to get a view of Spring
Lake to the northeast of the Grand
River mouth. Locate the area shown in Photo
23 on Map 10. (Hint: The power plant
can be seen in the upper left of the photo. Also, look for a bridge that
extends over a portion of Spring Lake
in the northeast portion of the map.) What is the name of the Bayou the
bridge crosses? What feature can you see in the lower portion of the
photo? (Hint: People constructed it.) Notice all the lawns
that surround Spring Lake.
How might they affect the water quality of Spring
Lake? Notice that the water
in Spring Lake
is not as brown as that in the Grand River. Why
might that be the case? Notice the hummocky (hilly) shoreline off in the
distance, along the Lake Michigan shoreline. Why
is the shoreline so hilly? Does examination of Map 9
along the Lake Michigan shoreline confirm your
17. As we continue north along the Lake Michigan
shoreline we come to the south end of Hoffmaster State Park
located between Grand Haven and Muskegon.
What kind of dunes are shown in Photo
24? Notice the vegetation present on the dune. If you could go
back in time, say 10 years, would you expect to see more or less vegetation on
the dune? Explain your reasoning. Now “go back in time” and observe
Photo 25, taken in 1990. Was your prediction
about vegetation cover on the dune 10 years ago correct? If not, give an
explanation for the amount of vegetation observed in 2000 versus that observed
18. As we fly further along the shore we see still more dunes like those in Photo 26. What evidence do you see indicating
erosion has occurred?
19. We continue north and come across a water intake structure south of Muskegon.
As you can see in Photo 27, riprap (large rocks)
has been placed along the structure in an attempt to prevent erosion due to
wave action. At the time of our flight (April, 2000)
you might expect wide beaches everywhere along the shoreline because lake
levels are currently very low. Indeed, wide beaches are present
along most of the region we have flown over. Yet, no beach is present in
front of the water intake structure. In fact, the conditions in front of
the structure look much as they did 10 years ago when the water level was much
higher (Photo 28). A beach is likely absent
in front of the structure because, during storms, waves reflect off the
riprap. The resulting high energy erodes sand from in front of the
structure and deepens the water. Once that happens, even larger waves can
approach the shore and erode sand away from the front of the structure.
(You may wish to review “Waves”.) One difference
that can be seen between the 1990 and 2000 photos is that sand is currently
being deposited on one side of the riprap (Photo 27).
On which side is sand being deposited and what does that tell you about the
predominant direction of littoral transport? (You might wish to review
"More about Longshore
Current and Beach Drift".)
20. The last lakeshore town we see on our flight is Muskegon.
Photo 29 is a view of the channel connecting Muskegon
Lake to Lake Michigan.
Using Map 11 determine the direction we were looking
when we snapped Photo 29. (The Muskegon
channel, dunes in Muskegon State
Park, and a portion of Muskegon
Lake, viewed from about the same
direction as Photo 29, can be observed in 3D Map 5,
which has an 8X vertical exaggeration.) In Photo 29 what is a likely
explanation for the difference in water color on either side of the
breakwater? (Hint: The channel is occasionally dredged to assure passage
of ships in and out of Muskegon Lake,
a deepwater harbor.) As we fly over Muskegon
State Park, we have one last chance
to view the beautiful, high sand dunes (Photo 30).
Dunes are found along various shores of the Great Lakes,
but most abundantly along the eastern shore of Lake Michigan.
Importantly, the high dunes formed due to unique geologic events that occurred
3,000 to 4,000 years ago during the Nipissing Lake
Stage. The high dunes are no longer forming today, so if they are
destroyed, they are gone forever.
21. As we fly over the Muskegon
harbor we see Grand Valley State University’s W.G.
JACKSON at its usual berth (Photo 31). (If you are
interested in learning about educational cruises aboard the JACKSON, see http://www.gvsu.edu/wri/education/.)
Find the location where the JACKSON
is berthed on Map 12. (Hint: The walk from
the Walker Arena to the JACKSON is
quite short.) If you wish to sample the sediment in Muskegon
Lake at a depth of 30 feet, how far
would you have to cruise from the JACKSON's berth to reach that point?
22. As we head southeast and fly back to Riverview Airport in Jenison, we
fly over lake plain (Photo 32), a flat area which
marks the floor of a lake that existed when the ancestral Great Lakes were at a
higher level. This reminds us that the Great Lakes
did not always appear as they do now, and that they represent a brief moment in
geologic time as all lakes have a limited lifespan. So as we end our
flight with the fantastic, high dunes off in the distance bordering the Lake
Michigan shoreline, we have a better appreciation for the Great
Lakes. List three things that are being done in the Great
Lakes region to protect this remarkable resource. What else
do you think should be done?
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LIVING WITH THE GREAT LAKES
BROUGHT TO YOU BY:
GRAND VALLEY STATE UNIVERSITY
DEPARTMENT OF GEOLOGY
ALLENDALE, MICHIGAN 49401