Soils and Geology of Wisconsin Field Trip, May 2008

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

Friday May 23

Berlin Rhyolite

On the east side of Berlin, three quarries adjoin the town cemetery. The quarries extract Precambrian rhyolite but two of them have Cambrian basal conglomerate preserved. This is the central quarry.
Left: Relic of quarry operations.

Below: Faint flow textures in the rhyolite.

Above: View of the north wall with rhyolite at the waterline and Cambrian conglomerate in the upper half of the exposure.

Left and below: closeups of the contact.

Standing on the contact
Flow banding is conspicuous on this weathered surface.


A deep flooded quarry in Redgranite.
Glacial striations and chatter marks on Post-Penokean granite.
Chatter marks
A conspicuous example of plumose fracture.
The spine in the center of the picture is a mafic dike that extends across the quarry.
Left: Flow banding adjacent to the dike contact.

Below: More views of the dike contact.

Lake Wisconsin Shoreline

Just west of Coloma, Highway 21 crosses from the recessional moraine onto the Lake Wisconsin plain.
The views here are looking east toward the edge of the moraine.

Ship Rock

A prominent joint runs the length of the rock, prompting Professor Luczaj to wonder if siliceous fluids hadn't percolated along the joint and made the rock more resistant to erosion.
Possible grinding holes at the base of the rock.

Witches' Gulch

I'll get you, my pretty, and your little dog, too. The witch's profile appears at left center.

Devil's Lake State Park

Setting up camp.

Saturday May 24

East Bluff

Barchan-like ripples

Southeast Moraine Dam

Devils Lake is dammed by a moraine at both ends. This is the moraine at the southeast end.

Devil's Doorway

Potholes Trail

The Potholes Trail offers a view of enigmatic potholes carved by running water, but there is no stream here now. Meltwater from glacial ice atop the bluffs probably carved them.
The Potholes Trail is about the steepest trail at Devil's Lake.
Transverse ripples with longitudinal grooves
Making tracks for the van.

Outside the Moraine Dam

The moraine dam fills the bedrock valley about halfway to the top. This viewpoint would have been under ice at the time.
Being a soil scientist means never having to wonder what's beneath the surface.
Prairie vegetation, check. Lake silt for parent material, check. Mollisol.

Parfrey's Glen

Devil's Lake

Views from the south end looking at the northern moraine dam

Below, left: the east bluffs. Below, right: the east bluffs and southeast moraine dam.

Skillet Creek

Baraboo quartzite at Skillet Creek. Excellent cross-bedding is visible here.
Slickensides on a small fault.

View of the Syncline from the North

Road construction forced a detour that resulted in a serendipitous view across the syncline from the narrow North Range.

Abelman's Gorge

Abelman's Gorge at Rock Springs is one of the best known geologic localities in the world. Once an abandoned quarry with iffy legal accessibility, it is now a state natural area.
A guitarist provided musical accompaniment. Rock music?
Wild Columbine
Above: Most of the good crystals have been mined out, but a few are visible in cavities Below: Quartzite breccia

Van Hise Rock

A shear couple. Demonstrating how the foliation formed.

Glacial Lake Baraboo

The dark soils left of the road are histosols, the much lighter soils to the right are mollisols.
Going out to investigate the histosols.
And back to camp.

Sunday May 25

Lower Narrows

The Lower Narrows are where the Baraboo River exits the Baraboo Range.
A large rhyolite boulder is typical of the rocks beneath the quartzite.
Close-up of the rhyolite.
North end of the narrows, looking east.
Foliation in the rhyolite.

Baraboo Interval Rhyolite

Road relocation has left outcrops on Highway 33 no longer accessible, but a few miles west of the Lower Narrows is an accessible location.
Looking north over glacial lake plain.
Small outcrop of rhyolite.
It really does seem to have been that kind of campaign. A tourist attraction in Wisconsin Dells.

Roche a Cri

Roche a Cri is one of the most dramatic of the castellated mounds in central Wisconsin.
Graffiti of all ages is carved into the rock, ranging from prehistoric to recent.
You can climb the north end of the rock.
It's a very long climb.
But the view is the reward.
Despite the castellated mounds, there's no getting around the fact that central Wisconsin is flat.

Rib Mountain

Mosinee Hill in the foreground, with Rib Mountain in the distance.
Lunch time.
Lichens on the quartzite.
™ Here come the men in black... ™ A number of picnickers were slightly freaked by seeing us pull up with a string of dark vans.
View west from the summit.

The quartzite monadnock at Rib Mountain was once believed to be the highest point in Wisconsin.

"When did it stop?" people repeatedly ask me. Well the Wisconsin Blue Book lists it in 1962, but Timms Hill in 1964, so, over 50 years?

How spheroidal weathering occurs in highly uniform quartzite is a mystery.
The quartzite is so uniform that bedding is all but impossible to see, but this ripple-marked surface furnishes a good indication.

Eau Claire Dells

Eau Claire Dells
Briefing on the geology
I have a photo of these potholes over 30 years old, and the difference in that time is close to zero.
How did graffiti from 1925 survive in a stream capable of polishing outcrops and creating potholes? Or was most of the carving done during glacial melt runoff?
Checking out the soil

Tigerton Dells

Below: Coarse granite of the Wolf River Batholith.
A pegmatite dike in the granite, with feldspar margins and a quartz center.

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Created 29 August 2008 , Last Update 15 January 2020