Ice Age Trail Glossary

For many long-time Ice Age Trail users, interesting new words become part of their vocabulary as they learn more and more about the Trail’s landscape and culture. Below are just a few of the terms you will find useful as you begin talkin’ Trail.

Barrens: Areas where pine and stunted oaks grow. Barrens made up 12% of the state’s original landscape. Found in prairie-like areas with sandy, infertile soil. Animals that inhabit barrens include whitetail deer, grouse, prairie chicken, redheaded woodpecker and timber wolf.

Bog: A wetland of spongy ground or peat, often with tamaracks and sphagnum moss.

Continental Glaciation: The formation, movement, recession and related effects of colossal, nearly continent-sized ice sheets. Though common during the Pleistocene (or most recent) Ice Age, the only ice sheets that today approach the enormity of those existing during the Ice Age are in Antarctica and Greenland. Continental glaciation sculpted a quarter of the Earth’s landmass and dramatically changed the Earth’s climate, oceans, plants and animals.

Dells/Dalles: A gorge cut by torrents of meltwater released by a melting glacier or draining of glacial lakes. Some dramatic examples: the Dells of the Eau Claire, the Wisconsin Dells and the Dalles of St. Croix.

Dolomite: A rock similar to limestone consisting largely of calcium magnesium carbonate.

Driftless Area: The southwestern quarter of Wisconsin is unglaciated or shows no signs of past glacial activity. It is a landscape deeply cut by ancient streams into narrow, angular valleys and several hundred million years old ridges. The best place along the Trail to see the Driftless Area is Dane County between Mineral Point Rd. and Table Bluff, west of the end moraine.

Drumlin: An elongated, teardrop-shaped hill. These streamlined hills were sculpted in the direction of the glacial ice movement. They often occur in groups known as swarms. Because drumlins generally form miles behind, or up-ice, from an end moraine, they are rare along the Trail. The Farmington Drumlins, in Waupaca County, is the largest swarm of drumlins along the existing segments of the Trail. A small group of drumlins is in Door County between Maplewood and Sturgeon Bay. State Hwy. 60, between Columbus and Hartford, and Interstate Hwy. 94, between Madison and Sussex, cross one of the largest drumlin swarms in the world.

End Moraine: A type of moraine formed at the outer edge of a glacier or glacial lobe where it paused or stopped. Prominent end moraines along the Trail can be witnessed at Prairie Moraine County Park in Dane County, Devil’s Lake State Park in Sauk County and the range of hills north and east of Antigo in Langlade County.

Erratics: Boulders carried long distances by the glaciers and deposited when the glacier melted. They tend to be smooth and rounded. Erratics can be found along the entire Trail, except where it traverses parts of the Driftless Area. Large, famous erratics along the Trail are in Walworth, Waupaca and Langlade counties.

Esker: A sinuous rounded ridge of sand and gravel deposited by the streams that flowed through tunnels at the base of the glacier. The Parnell Esker in Kettle Moraine State Forest–Northern Unit is the most notable example along the Trail. Other excellent eskers are in Polk and Taylor counties.

Extinct Glacial Lake: A glacial lake that drained, often catastrophically, when a glacier or glacial lobe melted back. Extinct Glacial Lake Wisconsin’s lakebed remains visible in Adams and Juneau counties. Much of the Fox Valley was for a time under Glacial Lake Oshkosh.

Fen: An area of low, flat marshy land where decomposing plants accumulate, forming peat.

Hummocky: Hilly, knob-and-kettle topography.

Ice Sheet: A large, continental glacier that is not confined by underlying topography. The northeastern quarter of North America was covered over a dozen times by the Laurentide Ice Sheet during the Ice Age, between 10,000 and 2.5 million years ago. Today, ice sheets are found only in polar regions such as Greenland and Antarctica.

Ice-Walled-Lake Plains: Mesa-like hills that were once lakes on a melting glacier. Streams flowing on the glacier deposited loads of sediment into these lakes. When the surrounding glacier had completely melted, the lake bottoms became the hilltops. Ice-walled-lake plains are showcased at the Chippewa Moraine National Scientific Reserve in Chippewa County.

Kame: A conical hill. Composed primarily of water-rounded sand and cobbles, these deposits were left by streams that flowed downward through shafts in the glacial ice. The Kettle Moraine contains the largest and most important kame fields in the world, particularly between Dundee and the Parnell Tower, near Slinger and at Holy Hill. Kames are intriguing because of their shape and the way they were formed, not because of their size.

Kettle: A surface depression formed by large, detached blocks of melting ice that were buried with sand and gravel. As the ice melted, the other material collapsed, leaving a crater-like depression. Some kettles are more than 100 feet deep. Kettles can be found in many places along the Trail.

Kettle Moraine: Also called the Interlobate Moraine, the Kettle Moraine is a series of ridges, 120 miles long and only a few miles wide, in eastern Wisconsin. The combined action and deposits of the Green Bay and Lake Michigan lobes of the continental ice sheet formed the Kettle Moraine. The Kettle Moraine is the birthplace of the Ice Age Trail and the subject of the first published study of interlobate glaciation in 1878.

Lobe: A tongue-like extension of an ice sheet. Six major lobes during the late Wisconsin Glaciation covered portions of Wisconsin. These lobes were the Superior, Chippewa, Wisconsin Valley, Langlade, Green Bay and Lake Michigan lobes. The Des Moines Lobe extended slightly into western Polk County.

Mammoth: An extinct species of elephant with hairy skin and long tusks curving upward that roamed North America, Europe and Asia. It is the Ice Age Trail mascot.

Moraine: A ridge formed by unsorted gravel, sand and boulders carried by the glacier and deposited at the outer edge, or front, of the glacier. Some are only 10 feet high, while others rise 250 to 300 feet. Moraines define the basic route of the Trail, and can be found in many places along it.

Outwash Plain: A sandy plain formed when glacial meltwater streams in front of glaciers spread over a very wide, flat area. The water swept the sand into both glaciated and unglaciated areas. Between Hancock and Plover, Interstate Hwy. 39 crosses part of a vast outwash plain. Another example is the Antigo Flats of Langlade County, visible along the Trail from the Harrison Hills of Lincoln County.

Pitted Outwash: An area of outwash that is dimpled with kettles. These areas were formed by blocks of ice that were carried by meltwater, deposited with sand and gravel and later melted in place, leaving kettles.

Potholes: A smooth bowl carved into bedrock by the grinding action of stones whirling around in a river eddy. Many potholes were formed by torrents of glacial meltwater during the Ice Age. The best place to see these along the Trail is near the western terminus in Interstate State Park. These potholes were formed when the St. Croix River was much deeper than today. Small potholes at Devil’s Lake State Park formed before the Ice Age.

Swale: A hollow or depression at the beginning of a valley that often has wet soils.

Terminal Moraine: A type of end moraine where a glacier or glacial lobe reached its maximum extent and melted back.

Tunnel Channel: Created by a fast moving river under a glacier that carves a valley. After the glacier has melted, the valley often contains a series of lakes. Prominent tunnel channels can be seen along the Trail in the New Hope–Iola Ski Hill Segment in Portage County and the Straight River Segment in Polk County.

Wisconsin Glaciation: A period of the Earth’s history at the end of the Pleistocene Ice Age, between 10,000 and 75,000 years ago. All glacial lobes and landforms described in the Ice Age Trail Companion Guide occurred or were created during the last part of the Wisconsin Glaciation, unless otherwise noted.