Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Photo of ledge © Eric Fowle

The pounding waves at Cave Point County Park in Door County slowly weather the fractured rock of the Niagara Escarpment.
© Eric Fowle

October 2010

A look at The Ledge

Celebrate the rocky ridge that cleaved glaciers, resists pounding waterfalls and forms the terroir for fine wines.

Joanne Kluessendorf

Wisconsin owes a lot to its rocks, even its name. Derived from the Miami Indian word meskonsing meaning "river running through a red place," the state's name pertains to the red sandstone bluffs that border the Wisconsin River. Lead mined from rocks around Mineral Point attracted the first European settlers to the territory and led to statehood. Later finds of copper and iron fueled the state's economy. Lime, building stone and aggregate are the literal foundations that built its cities and towns. Soils enriched by rocks that were ground up by glaciers support agricultural bounty. And then there's the scenery – lakes and rivers, hills and valleys, bluffs and ledges – it's the rocks, the geology, that make Wisconsin such a special place.

Behold the Niagara Escarpment

Though many western states sing the praises of their mountains, mines and canyon lands more loudly, Wisconsin is home to some world-famous geologic features, too. One of the most renowned is the Niagara Escarpment. This prominent rock ridge stretches nearly 1,000 miles in an arc across the Great Lakes region, forming the ancient "backbone" of North America. It extends from eastern Wisconsin through Michigan's Upper Peninsula, into Ontario, Canada (where it is designated a World Biosphere Reserve), and on to western New York where Niagara Falls cascades over it, giving the escarpment its name.

In Wisconsin, the Niagara Escarpment is called "The Ledge" or "The Bluff" locally. It extends about 250 miles through the eastern part of the state. Beginning with a few isolated outcrops in Waukesha County on the south, the escarpment then disappears under glacial sediments until it re-emerges in Dodge County. It is well exposed in Fond du Lac County. In Calumet County, it is most conspicuous at the northeastern corner of Lake Winnebago. From here it continues into Brown County where it skirts the eastern shore of Green Bay. The most prominent and highest exposures in Wisconsin rise above the bay on the west side of the Door County peninsula.

The escarpment has had a lot to do with creating the familiar landscape of eastern Wisconsin. During the last ice age, this erosion-resistant rock ridge caused the vast glacier to split into two lobes, which carved out Green Bay, Lake Winnebago and Lake Michigan. It continues to lend a special sense of place to the region, as it snakes through the countryside, affording a dramatic backdrop here or a spectacular view there. Early Native Americans revered The Ledge, using it for burials, ceremonies and other sacred purposes. As many as 500 sites are known on the escarpment in Wisconsin where Native Americans left behind structures, symbols and implements.

Centuries later, when European settlers arrived, the escarpment became important economically for its natural resources. Soon, The Ledge was lined with limekilns, in which rock was burned to produce the white lime powder that settlers needed for mortar, plaster and paint. The well-layered rock of the escarpment yielded excellent building stone for barn and farmhouse foundations, as well as for churches and business buildings in the burgeoning new towns and cities. Iron ore deposits in Dodge County were mined to produce the cast iron for kitchen stoves and many more "modern" conveniences.

More recently, other important aspects of the escarpment have been uncovered. Its unique fauna and flora includes 240 rare, threatened or endangered species, such as lichens that grow on stones, crevice-clinging ferns, and species of tiny land snails – relicts of the last ice age – that thrive in the cool shaded cliff face and talus slopes. Its fractured rock and thin soil cover are important in sustaining groundwater quality. Its natural beauty attracts tourists, helping Door County to be voted one of the top 10 vacation destinations in the United States.

Photo of ledge crevice © Eric Fowle
Autumn leaves spill into the blocks of rocks and crevices at High Cliff State Park in Calumet County.
© Eric Fowle

In recognizing its significant role in Wisconsin's natural and cultural history and to draw attention to its international scope and global importance, the State Legislature proclaimed 2010 the Year of the Niagara Escarpment to "foster awareness and education on this important and unique landscape feature." In celebration, a variety of events and activities from museum exhibits, to jazz festivals, to wine and beer tastings, already have been held along the escarpment and will continue throughout the year and beyond. Fall and winter are perhaps the best times to appreciate the escarpment for its natural beauty, as an elemental piece of our landscape, and to enjoy some of the more unique ways to view The Ledge.

View from above

In eastern Wisconsin, the Niagara Escarpment satisfies a longing to see above the trees and sense the lay of the land. You'll find one of the most magnificent viewscapes in the area at Ledge Park in Dodge County. This 83-acre county park lies at the southeast corner of Horicon Marsh, the largest freshwater cattail marsh in the country. Both a state wildlife area and adjoining national wildlife refuge, Horicon Marsh has been designated as a Wetland of International Importance and a Globally Important Bird Area. There is no better place to get a sense of the size and scope of Horicon Marsh than from atop the escarpment, which rises 250 feet above the wetland. Like Lake Winnebago, Horicon Marsh is a remnant of the much larger glacial Lake Oshkosh that formed when melting ice flooded the area and was kept from flowing east by the escarpment itself.

One of the most remarkable sights to see from this vantage point on the escarpment is the spectacle of the Canada goose migration. Every fall, these birds leave their breeding grounds near Hudson Bay in Canada and congregate at Horicon Marsh between mid-September and mid-December before heading to their wintering grounds in southern Illinois. Their population peaks in late October to mid-November, when as many as 200,000 geese rest, stage and temporarily reside. The site and sound of hundreds, even thousands, of geese in orderly V-shaped formations approaching the marsh from every direction is awe-inspiring. Considered one of the most amazing wildlife displays in the Midwest, nature lovers migrate here from across the country and the world to view the event right in our own backyard. Hike the Ledge Overlook Trail in Ledge Park on a crisp autumn day to watch and hear the countless birds silhouetted against the rose-colored sunset. It is a sight you will not soon forget.

Not far from Ledge Park, iron ore was mined from the escarpment beginning in themid-1800s, when the deposit was proclaimed "inexhaustible." By the late 1930s, all mining had ceased. The underground mine at Neda, inactive since 1914, has become one of the largest bat refuges in the Midwest, with about 143,000 bats hibernating there each winter. To learn about the iron mining era, visit the Limestone School Museum in Mayville to view the new "Iron Country" exhibit.

View from below

This fall, get a good look at the inside of the Niagara Escarpment, which is home to the largest number of underground caves in Wisconsin and two of the three longest cave systems in the state. The vertical tension fractures that crisscross the surface of the dolomite bedrock in The Ledge have acted as a conduit for water flow for millions of years. Rainwater, groundwater and glacial meltwater have dissolved rock along the fractures and, with waves, ice and frost, have worn away the rock physically. Water also flows along horizontal gaps between rock layers. Together, these weathered features are called karst, which includes caves as well as sinkholes.

Some of the caves formed by waves are best seen in Door County. Eagle Cave in Peninsula State Park on Green Bay lies high in the bluff, formed when lake levels were much higher during the last ice age. In contrast, the sea caves at Cave Point County Park are still being created by the thundering waves of Lake Michigan. On land, most of the caves filled with sediment over time, but some have been dug out and are accessible to the public. From May through October, guided tours are provided at Maribel-Cherney Caves County Park in Manitowoc County and at Ledge View Nature Center in Calumet County. This year, Ledge View offers its family-oriented Halloween Candlelight Cave Tour on October 22 and 23. And, remember, no matter what the weather outside, the caves maintain a fairly constant temperature around 52°F.

View the color

As Europeans emigrated to eastern Wisconsin beginning in the mid-1800s, forest and woodland were cut for fuel and lumber so the land could be plowed and planted. The rugged cliffs of the escarpment were not easily logged or farmed. Consequently, a substantial amount of native vegetation is preserved on the edge of The Ledge today. With roots delving into fractures in the rock, stunted and gnarled cedars cling to the face of the rocky cliffs. Among the oldest trees in eastern North America, these ancient cedars form a vertical forest. Even though the cedars are starkly beautiful and reveal climates of long ago, the trees growing on the ledge top attract the most attention in autumn. As their leaves turn shades of crimson, saffron and claret, the ash, beech, birch, maple, oak and other hardwoods seem to set The Ledge ablaze.

Although you can enjoy fall foliage anywhere along the escarpment, this might be a good time to drive Wisconsin's newest scenic byway, the 66-milelong Coastal Byway in Door County, which was established in May of this year. While on the peninsula, visit the Fall Fest in Sister Bay on October 15-17; it's the oldest and one of the largest celebrations in Door County. The Fond du Lac Audubon Society rewards children with a special patch for visiting five of nine escarpment sites listed in their free "Ledge Passport" through November 13. Bring the family to High Cliff State Park on October 30 for the free Great Pumpkin Hike, which includes pumpkin carving, wagon rides and a torch-lit hike along the ledge.

View from afar

As snow begins to fall, the escarpment presents yet another expression, with the somber gray dolomite cliff face now resembling the ramparts of a castle – a defensive wall built to thwart ancient invaders. No longer hidden by vegetation and with a dusting of white, the path and extent of the escarpment becomes most obvious in winter. Suddenly, The Ledge emerges from the middle of fallow farm fields, in stream banks, along roadways and behind subdivisions. In places, The Ledge appears to be long, continuous and knife-edged. Elsewhere it occurs as a series of isolated, irregular rock remnants that meander across the countryside. The varying height of the escarpment along its discontinuous passage also becomes evident in winter.

The sparkling solitude of a fresh snowfall presents special opportunities to enjoy the escarpment.

Photo of ledge in winter © Eric Fowle
On a winter drive it's easy to follow The Ledge from Dodge County north.
© Eric Fowle

At High Cliff State Park, take to the snowshoe trail that passes the historic limekiln ruins above Lake Winnebago, with its colorful ice-fishing shanties. Experience cross-country skiing by candlelight at Peninsula State Park and Ledge View Nature Center. For a little more excitement, ride the snow-tubing hill at Calumet County Park, just next door to High Cliff.

Frozen in time, waterfalls in winter are especially beautiful with their glacial-blue color and extraordinary ice formations. Many of Wisconsin's waterfalls are located along the escarpment. Fonferek's Glen and Wequiock Falls, both Brown County parks, are easily accessible and offer great views. The new boardwalk at Wequiock Falls makes for an easy walk into the ravine close to the falls.

View from the vineyard

By year's end, Wisconsin may have a new federally designated American Viticulture Area (AVA) named for the Niagara Cuesta. This broad slope associated with the escarpment is blanketed with well-drained glacial sediments and influenced by unique microclimates and weather patterns moderated by the escarpment and by its proximity to the waters of Green Bay, Lake Winnebago and Lake Michigan. This combination of factors mimics some of the best grape-growing regions in the world, including that of Bordeaux, France. Wineries associated with Wisconsin's escarpment already are winning medals in national competitions. When the AVA designation is received, lift a glass of escarpment wine and toast Wisconsin's rocks.

Joanne Kluessendorf is fouding director of the Weis Earth Science Museum in Menasha, Wisconsin's official mineralogical museum. A native of Milwaukee, Kluessendorf received her doctorate in geology at the University of Illinois at Urbana-Champaign. She loves the ledge, and has studied its geology for many years.