Wisconsin Geology Gallery

IMPORTANT NOTICE: All photos are copyrighted by Raymond Wiggers. If you are an educator or student and would to like to use any of these images, e-mail me and let me know how the images will be used. Please also credit me as the photographer. I ask that all companies, organizations, and government agencies contact me about my fees for the use of my photos, and about obtaining higher-quality versions on CD-ROM. Thanks for your understanding and compliance.

To go directly to a particular state represented in this gallery, click on its name below:

- Amnicon Falls State Park (Douglas County)

- Clark County

- Copper Falls State Park (Ashland County)

- Devil's Lake State Park (Sauk County)

- Door County (Not Including Its Parks)

- Grant County

- Jefferson County

- Juneau County (Not Including Its Parks)

- Kenosha County

- Marinette County

- Peninsula State Park (Door County)

- Rocky Arbor State Park (Juneau County)

- Sauk County (Not Including Its Parks)

- Waukesha County

- Whitefish Dunes State Park (Door County)

3. The person who named this stream the Bad River was impervious to its many charms. Here the water tumbles and plunges over 1.1-billion year-old outcrops of basalt and sedimentary rocks similar to those of Upper Michigan's Keweenaw Peninsula. Their origin is traced to the development of the Midcontinent Rift.

1. This park is one of the best places to examine evidence of the Midcontinent Rift, which may have been one manifestation of the breakup of the supercontinent Rodinia approximately 1.1 billion years ago. (The much more frequently cited supercontinent Pangea would not come into being for another 800 million years.) Here, amid Proterozoic- Eon outcrops and handsome waterfalls, is the Douglas Fault. Its trace on this photo is the dark diagonal line that runs from upper left to lower right. The wedge of rock above, known as the hanging wall, is basalt that has been thrust up a great distance over the sandstone footwall. In the heavily vegetated Midwest such a clearly defined fault exposure is a rare thing indeed.

26. At the park's northern end. Here the Lake Michigan shore changes abruptly from a depositional beach to a rocky, erosional coastline, where dolostone of the Silurian Engadine Group forms a low, wave-cut terrace. Note the high, vegetated dunes in the distance. The park is a good place to find such boreal plant species as yellow birch, mountain maple, and buffaloberry.

27. At the same spot as the preceding photo. This large, concentric pattern and others like it in the dolostone have been interpreted as cross sections of stromatolites -- dome-shaped structures of colonial bacteria and algae that grow in shallow water. Stromatolite fossils are much more common in older rocks of Archean and Proterozoic age, because the organisms that formed them later became food for browsing snails and other Johnny-come-lately animals. If these structures are indeed stromatolites, they suggest that the local marine conditions in the Silurian were either very salty, or that there were other factors (strong currents?) that discouraged the presence of predators.

4. The Baraboo Range, in Sauk County, is one of the Badger State's chief claims to earth-science fame, and with good reason. Here an exhumed archipelago of Early Proterozoic quartzite, protruding out of a thick apron of Cambrian and Ordovician strata, forms a ring of picturesque hills that contain examples of many geologic processes, structures, and landforms. The park is the centerpiece of this region. This photo shows the Devil's Doorway, one of the striking erosional remnants to be seen on the lake's East Bluff.

5. Along the Balanced Rock Trail, Devil's Lake State Park. As this large, lichen-dappled talus block on the East Bluff shows, the Baraboo Quartzite, at least 1.9 billion years old, was originally sandstone that had ripple-mark structures formed by running water. These ripple marks survived the rock's subsequent metamorphosis into quartzite. The walking stick in the photo shows scale; the distance between the two green stripes is half a meter (50 centimeters). The bluff slope of the park are remarkable for their huge talus (rock debris) fans. These features were probably formed during the pronounced freeze-thaw cycles of the Pleistocene Epoch.

20. On the north side of the Baraboo Range, at Rock Springs. This is the Kaaba of geologists -- the Van Hise Rock. It appears to be a slump block fallen from the nearby cliff of the Upper Narrows of the Baraboo River, but it's actually an isolated section of bedrock, still attached to the Earth's crust. Visible here are two contrasting layers of metamorphic quartzite and phyllite. They have been tilted into an almost vertical position by powerful compressive forces operating during the the collision of continental plates that created the Penokean Mountains farther to the north. Also visible on the Van Hise Rock are important telltale "slaty cleavage" marks. They show how the compressional stresses were refracted through the two different rock types present here.

21. A short walk from the Van Hise Rock towards Rock Springs town center brings you to an old quarry where there is a breathtaking exposure of ripple marks in the Baraboo Quartzite. These ripple marks were originally formed on a horizontal surface. As they now demonstrate, the rock layers here dip southward at a very steep angle. Across the basin, in the south part of the range, the rock layers dip northward at a much shallower angle, as can be seen at Devil's Lake. The result is a regional structure called an asymmetrical syncline -- where the layers of the Earth's crust plunge down on one side and come back up on the other. It's similar to a downward-facing pucker in a rug that has been pushed inward on both sides.

11. This hump-backed hill, another drumlin, is one of hundreds in Jefferson County and other parts of southeastern Wisconsin. Drumlins characteristically occur in swarms. Within one area they are all oriented in the same general direction. Drumlins were formed when a continental ice sheet overrode preexisiting glacial drift or bedrock and streamlined it into shapes reminiscent of surfacing whales. The tapered, shallow slope of each hill points in the direction the glacier was moving; the "upglacier" side is the one with the much steeper, abrupt slope. The right side of this photo is very approximately north. Given that fact, it's an easy task to determine which way the ice sheet was headed.

24. Yet another drumlin, in the Delafield area of Waukesha County. There are some outstanding glacial landforms in this area, but they are rapidly being obscured by the uncoordinated clutter of suburban sprawl. That sprawl is in turn a classic American manifestation of severe human overpopulation. This peaceful scene seems miles and miles from the nearest Starbuck's, but in fact new "developments" are just down the road. Many have speculated how these unsightly housing compounds spring up so quickly; my favorite theory is that they spread by spores wafted on nighttime breezes. By morning, the spores have fully germinated. The day before, the lot was a farm field; now it has two hundred bloated, hangarlike houses with a pathetic little pond, ugly wooden decks, and no front porches. Of course, this destroys the landscape, but most of us stopped caring about that a long time ago.

10. The great geological story to be found at this gravesite in the small town of Hazel Green is not the handsome, polished granite headstone, but the person it commemorates. In this cemetery plot, lie the remains of the man Badger State contemporaries called "Old Stone-breaker" --James Gates Percival, one of the most remarkable if sadly forgotten intellectuals of nineteenth-century America. Besides serving as state geologist for both Connecticut and Wisconsin, Percival was an acclaimed poet, a linguist, a physician, and a lexicograph-er who at one point in his often poverty-stricken career assisted Noah Webster with the compilation of the Dictionary of the American Language. Percival, who often had troubled relations with the rest of his species, ended his days among the Hazel Green townsfolk, who apparently accorded him great respect for his knowledge and broad-ranging accomplishments.

2. A block of Archean-Eon gneiss near an outcrop of the same rock on the shore of Lake Arbutus. According to Wisconsin geologist Gene LaBerge, this gneiss is at least 2.8 billion years old and may be 3.2 billion. Whatever its exact age, it is very old and seems to represent part of the ancient core of an "exotic terrane" that collided with the ancestral heart of North America. In other words, this highly metamorphosed gneiss is one of the older rock units surviving on Earth, and it didn't start its unimaginably long journey as part of this continent. At present, probably the oldest rock unit that has been dated is the Acasta Gneiss, from northwestern Canada. It is approximately 3.9 billion years old.

17. Light-colored granite veins cutting through somewhat older and darker metamorphosed volcanic rocks, about four miles south of the town of Niagara. This roadcut shows nothing less than a portion of the exposed roots of the Penokean Mountains, a lofty range created by the collision of the Superior section of ancient North America with an island arc and then another continent about 1.9 billion years ago.

9. In the northern part of the Door County, near Rowleys Bay. The low rise in the middle ground is a drumlin -- a deposit of glacial drift streamlined by the left-to-right motion of the Wisconsin glacier. In contrast to their counterparts in southeastern part of the state (see Photos 11 and 24, below), these drumlins are quite small.

18. A perched wave-cut cliff (center), along the shore of Green Bay (the inlet which gives the city south of this locale its name). Elevated notches in the coastlines of the northern Great Lakes are a common sight. They were formed when the water surface stood higher relative to the land. Apparently two factors were involved: at various times there has simply been more water in the lake basins; and the Earth's crust has actually rebounded somewhat in the centuries following the demise of the Wisconsin ice sheet.

25. This park, one of the Door Peninsula's best geological and botanical locales, has a certain numinous quality I fail to define but feel on every visit. The dunes here are some of the largest on the western shore of Lake Michigan. The migration of this particular dune has been halted by a mantle of vegetation that includes everything from ground-hugging lichens to lofty paper birches. However, park users have blazed a "desire line" that partially undoes the patient work of the plants and other dune inhabitants.

8. Old Stone Quarry Park, just north of Sturgeon Bay. The quarry was excavated into the Silurian escarpment, a cuesta that runs up the eastern side of Wisconsin, around the southern shore of Michigan's Upper Peninsula, and through Lake Huron country to Niagara Falls. A cuesta is a ridge with a steep foreslope and a shallower-angled backslope.

12. At Camp Douglas. This castellated hill, in common with about fifty other places in the Midwest, is called Castle Rock. Made of sugary Cambrian-Period sandstone, this highly dissected butte and others like it in this area were once islands in the proglacial Lake Wisconsin. Nowadays, it stands nexts to Interstate 90/94.

14. . . . as these young hominids demonstrate. I've always found the human urge to despoil the landscape simul-taneously sacrilegious, pathetic, and fascinating. The urge seems to be compulsive and closely related to what dogs have to do at fire hydrants.

6. The famous potholes on the south face of the East Bluff. While potholes are a fairly common sight in places there are waterfalls, geologists have debated for years about these unusually enigmatic features. Were they formed in the waning days of the Wisconsin glacier, less than fifteen thousand years ago? Or do they date from Cambrian Period or even the late Proterozoic Eon, half a billion or more years ago? Whatever their age, they are notable that they formed at all, given the great hardness and durability of the Baraboo Quartzite. The walking stick provides scale; the distance between its top and bottom green stripes is one meter.

22. An outcrop of sandstones south of the Baraboo Range, along County Highway C, just west of Denzer. This is part of the Cambrian-Period sedimentary rocks that flank the Baraboo Range. The upper, olive-tinted strata belong to the Tunnel City Formation; the lower, white layers to the Galesville Member of the Eau Claire Formation. The Tunnnel City's coloration is partly due to the presence of glauconite. This mineral forms in an environment where there is only a modest amount of sedimentation and abundant mineral matter, usually in the form of fecal pellets of marine organisms.

23. A closeup of the Tunnel City-Galesville contact. The lowest part of the Tunnel City, the dark horizontal layer in the center, is rip-up conglomerate, composed in part of chunks of the underlying Galesville sandstone. The latter member contains vertical burrows of marine animals. In modern times it is also home to photosynthetic cyano-bacteria that use the light that passes through the translucent sand grains.

15. Manipulating a dynamic coastline. The Lake Michigan shore at Kenosha's Kennedy Park. Large blocks of locally quarried Silurian dolostone, over 400 million years old, have been placed in an interlocking grid. This serves as a rip-rap barrier to protect the fragile shore from the onslaught of the waves.

16. Along Kenosha's lakeshore, at the sandy mouth of the Pike River. Here members of a recently arrived species make use of our planet's special gift: the liquid form of water, the universal solvent. The fact that our planet has retained its precious supply of this remarkable substance throughout its geologic history has made all the difference. It has powerfully contributed to the way our planet's basic processes proceed; and it has provided the crucial matrix for over three and a half billion years of organic evolution. We must be careful not to take this magical mixture of hydrogen and oxygen for granted. We foul it at our own grave peril.

19. One does not have to be a back-to-nature fanatic to revolted by what we have done to the Wisconsin Dells, a vastly depressing example of landscape desecration and lowest-common-denominator money-grubbing gone amok. But just up the road from that abomination lies this park, a peaceful and secluded remnant of pre-tourism days. Along the lower trail the hiker skirts a bluff of Cambrian-Period sandstone and the lush wetland below it. This slump block fallen from the bluff, which on closer inspection shows excellent crossbedding patterns, is now a perch for trees that manage to find enough sustinance in the thin soil that has developed on its upper surface.

Would you like to learn more about the geology of this diverse and fascinating state? Check out my Courses, Tours, and Lectures Pages for educational events focused on the

Earth science of Wisconsin.