Soils and Geology of Wisconsin Field Trip, May 2009

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay

Monday May 18

Back Forty Mine

Loading up at UWGB
First stop: Aquila Resources in Stephenson, Michigan for a talk on their massive sulfide mine project.
Not everyone is happy about the idea.
There are outcrops in there somewhere
Out at the field office.
Bob Mahin of Aquila Resources describes the outcrops.
Left: Professor Luczaj answers questions.

Below: iron-stained outcrops. Like most of the other massive sulfides of the region, the host rocks are rhyolite.
Drill holes made during mapping of the ore body. Several holes at differing plunges were drilled at many localities.
Gossan is a cap of iron oxides that typically forms over ore deposits due to weathering. Exposed gossan at newly discovered ore bodies is extremely uncommon. Most of the surface discoveries have long since been made.
The core storage area. Bob Mahin explains the drilling program. The yellowish material in the top third of the core on the ground represents about a hundred feet of pyrite and sphalerite.

Marek Road

It was a long morning and we had a late lunch.
Penokean metavolcanic rocks on Marek Road.
The rocks are pretty much featureless on fresh surfaces but show textural features on weathered surfaces.

Pemene Falls

Andrea Duca, who lives in the area, wrote up outcrop descriptions as her project in Field Methods. Here she gives the group an orientation.
The rocks here are greenstones of the Pembine-Wausau Terrane
The falls.
Breccia zone
C'mon, hurry up! Turn into soil already!

Kevin Fermanich examines some of the soil

Piers Gorge

Piers Gorge on the Menominee River is part of the Niagara Fault Zone
Views of the outcrops.
Below: potholes along the shoreline.
View of the rapids in the Menominee River. Wisconsin is on the opposite shore.
Although the rocks here are mapped as metavolcanic, they look much more like the Michigamme Formation north of the fault. The map may not be accurate here.
Hey, it's a histosol!

Menominee River at Niagara

An impromptu stop to look at the cliffs at Niagara. The Niagara Fault is half a mile or so north of the cliffs here, and the river flows along the contact between the softer Quinnesec schist and more resistant metadiorite that makes up the cliffs. We're in Wisconsin here, with Michigan across the river.

Lake Ellen Kimberlite

A stop in Iron Mountain for groceries.
The hunters and gatherers return from hunting and gathering.
The kimberlite is exposed in a small cut
This is it?
The kimberlite contains blocks of Ordovician dolomite (white), demonstrating both its Phanerozoic age and the fact that the dolomite once extended this far west.
"Any diamonds yet?"
"Nope, how about you?"

Below: back to the vans

Archean Granite Gneiss

Archean granitic gneiss just south of Republic
A mafic dike with dramatic differential erosion.
Pegmatite dikes.
Below: One dike has a large inclusion and a shear zone along the margins.
Basalt dike cutting granitic dikes. An exercise in cross-cutting relationships.

Proterozoic Rocks

In contrast to the scarcely deformed Archean basement, the Proterozoic sedimentary rocks were intensely deformed during the Penokean Orogeny. There are numerous isoclinal folds in the outcrops.
When rocks are extremely flattened in one direction, they usually stretch in another. The pinching and swelling layers on the right side of the outcrop show boudinage (from the French for sausage) due to being pulled apart.

Lee wasn't entirely flattered to discover she was being used for scale in the photos!

Below: Van Riper State Park is a convenient place to camp out.

Tuesday, May 19

We managed to finish breakfast and break camp before the rain hit, although one tent got well soaked.

This was a miserable day. It barely hit 40 and was wet most of the time, though fortunately we didn't get rained on heavily.

Michigamme Mine

This mine is being buried by a highway widening project. The rock has been retrograde metamorphosed to chlorite greenstone and has abundant pseudomorphs of garnet, a few of which were still exposed.

This is why you document localities. They may not be there a few years later.
Iron being deposited by iron-metabolizing bacteria, a relic of how Precambrian iron ores probably formed.

Champion Mine

Left: a road made of specular hematite gives a new meaning to the term "road metal."

Below: the mine dumps.

Geologists in the Mist

Jasper Knob in Ishpeming preserves spectacular banded iron formation.
It was cold and wet.
The banded iron formation here is spectacular. Back when the mines were open, "iron ore" meant massive hematite, and this iron ore was too finely disseminated to be recoverable. Thus the core of the deposit was mined out and the peripheral banded iron formation was left behind. Fortunately for us.

Pillow Basalts

Archean shields tend to be dominated by granitic rocks and troughs of pillow basalt indicating underwater eruption.
Weathered surface showing pillow texture.
Truncated pillows on a glacially polished surface.
Undersides of pillows

Presque Isle Park, Marquette, Michigan

Iron ore dock
Jacobsville Sandstone makes up the top half of the cliffs, with an enigmatic Archean peridotite making up the bottom half.

Below: compare the cliff in 2006 (left) with 2009 (right).
The peridotite is accessible on the north shore.
Left: colorful lichens on a rock face. Note the remnant ice patches.

Below: waves breaking on the rocks.

Spheroidal weathering of peridotite.

Marquette Synclinorium and Kona Dolomite

Distant view of Presque Isle
Above: the prize outcrops are hidden in the woods. Below: world-class stromatolites are visible here.
Left and below: a deep road cut dramatically exposes the north limb of the Marquette Synclinorium.

Laughing Whitefish Falls

Supposedly the falls is named because of a rock formation that looks like a laughing whitefish. We concluded the whitefish was doing a Nelson Muntz "HAH-hah" at hapless visitors.

This is the good road.
And this is the bad road.
The overlook at the falls.
A slightly more resistant series of sandstones creates a cliff with numerous overhangs.
The falls drops over the upper cliff then forms a smooth cascade down the uniform rocks below. Most of the falls in this region have a similar form.
Looking down the falls.
Dutchman's Breeches

Whitefish-Au Train Spillway

When ice still blocked the outlet of Lake Superior, water spilled down the valleys of the Au Train and Whitefish Rivers to Lake Michigan, carrying red sediment which the Valderan and GreatLakean readvances then tracked all over northeastern Wisconsin. Kevin Fermanich is discussing the hydrology of this dam on the Au Train River.

Below: views upstream

Looking west toward the edge of the channel.
Au Train Falls flows down the Ordovician Au Train dolomite. The falls are unfortunately marred by a penstock pipe.
Looking across the channel.
In the bottom of the channel.
Hiking up the side of the channel to compare upland soils with the channel bottom.
Trout lily.
View across the channel.
Kevin Fermanich waxes poetic about the soils.
Now that's an E horizon!


Above, settling in at the Munising Tourist Camp. Below, why you should always use a dictionary. "Das gift" means "poison" in German.
Lighthouse in Munising
View from the overlook west of town

Below: one last spot of cheer.
Huddling for warmth. We barely saw 40 all day.

Wednesday, May 20

Today was a dramatic improvement, with temperatures more than 40 degrees warmer than the previous day.

Below: At the overlook west of Minising.

View of Grand Island

Munising Falls

Above: the marsh marigolds look almost deliberately planted for effect.

Below: the falls drop over Cambrian sandstone.

Terraces near Wetmore

Forest fire spotting tower. Once these were a common fixture of forests, but cell phones and remote sensing have rendered them largely (but not entirely) obsolete.
In this part of the world, pretty much all the upland soils are spodosols.
This forest is so open because it was selectively logged of all its biggest trees, as shown by the stumps.
Looking down from a terrace. We were not sure if the terraces were wave cut or marked ice margins.
Looking back at the step. The highway has a gentle grade but in the woods the step is very steep.

Sable Falls

The pebbles are so much more colorful when wet.
Professor Fermanich draws a line in the sand.

The Log Chute

An old cabin is being allowed to return to nature.
A beautifully picturesque group of trees on the edge of an old field.

Below: on the trail to the overlook.
Equipment for the logging trade. At left is a sleigh. Winter once was the best time for logging because the surface was frozen and more passable. The big wheel log hauler on the right helped make summer looging feasible.
  Perfect time for flowers.

Below: the overlook.
Stratigraphy in the dunes.
At one time this man-made ravine was lined with logs and used to slide logs down to the shore for shipping. There do not seem to be any photos of the chute in operation and the log skids have long since vanished.
Left: trees being buried by the dunes.

Below: the U.P. offers wonderful geology interspersed with vast tracts of non-geology.

Chapel Falls and Chapel Rock

There's nothing like a ten-k hike to cap off a good day in the field.
We were intrigued by this bench
Large erratic
A rose-breasted grosbeak dropped by.
Marsh marigolds were everywhere.
Chapel Falls marks the halfway point on the trail.
Like most of the falls in the region, it has a slightly resistant lip with a smooth cascade in the nearly uniform rocks below. With no great contrast in hardness, we don't see vertical drops or plunge pools.
The woods were straight out of a Disney film with near solid carpets of flowers in places. Bambi, Thumper and Godzilla had prior commitments so we didn't see them.
The goal of the hike was Chapel Rock on the Lake Superior shore.
Enormous cross beds are visible in the Cambrian sandstones.
I had to go and rile things up by pointing out that the beds are awfully conglomeratic to be dunes. If they were simply sandstone we'd conclude this was dune cross-bedding in a heartbeat.

Thursday, May 21

Perched Outwash Plain

South of Munising is an area of perched outwash plain, outwash elevated above the surrounding terrain because it was confined by ice. So we go in to investigate the soils.
Anyone ever see the movie "Holes?"
Praying to the soil gods.
And its a spodosol, with unweathered outwash sand beneath it.
Looking down off the outwash plain.
Looking back at the edge of the perched outwash plain.

Burnt Bluff Formation

A quarry and outcrop just north of Manistique give about the only view of outcrop between Manistique and Munising. The Burnt Bluff formation is a finely laminated near tidal deposit.

Big Springs (Kitch Iti Kipi)

This remarkable spring is just west of Manistique.
A boat allows visitors to view the depths of the spring.
Even better than a glass bottomed boat is a no-bottom boat. An open well offers views of the bottom, over 40 feet down.

A UW-Milwaukee field trip led by Professor Bill Kean was also here.

Stephenson Drumlins

I'll take Histosols for $200, Kevin.

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Created 22 May 2009 , Last Update 15 January 2020