Driftless Area

The upper midwest "Driftless Zone"
(Also known as " Driftless Area" or "Unglaciated Area")
The "Driftless Area" of the Upper Midwest derives its name from the fact that it was unglaciated during the most recent glacial event about 12,000 years ago. Glaciers surrounded but did not pass over this land. Portions of Iowa, Wisconsin, Minnesota and Illinois contain unusual geology. This karst region, also referred to as the Driftless Area, the Coulee Region or the Driftless Zone, escaped the last glaciers leaving the Paleozoic-age bedrock subject to erosion which helped create a curious topography of steep slopes and cliffs.
The Driftless Zone is an area of about 20,000 square miles in western Wisconsin, northeastern Iowa, southeastern Minnesota, and extreme northwestern Illinois, which was by-passed by the continental glaciers. As a result, the topography is more rugged than that usually associated with the Midwest. In Wisconsin, the Driftless Zone parallels the Mississippi River to the Illinois state line in a band 60 to 80 miles wide. About halfway a lobe extends farther northeast into Wisconsin. In Iowa, it also parallels the Mississippi River from the Minnesota state line to about Dubuque in a band approximately 20 miles wide.The Minnesota and Illinois portions are much smaller, by comparison, and much more irregularly defined. In addition to the curious topography of steep slopes and cliffs, there are unique habitats, the algific (cold air) talus (loose rock) slopes. These slopes remain cool throughout the year and are home to rare species of plants and animals.
These slopes are usually north facing, are covered with a talus layer that allows ice-cooled air to exit from underground cracks and fissures. Upland sinkholes contribute to the air flow regime and are an important component of a unique system called an algific talus slope, meaning a cold producing rocky slope. Even when the outside air temperature is 90 °F (32 °C), ground temperatures on these slopes range from close to freezing (32 °F, or 0 °C) to about 55 °F (13 °C). Although the slopes will freeze in winter, the temperatures are moderated. These slopes remain cool throughout the year and are home to rare species of plants and animals.
The area known as the "driftless area" is notable as the further most edge of the glaciers' advance. Where the towering walls of ice stopped and then receded, the rock formations were formed.
As the ice moved, it froze around grains of sand, pebbles, and boulders, picked them up, and carried them along. The material frozen into the base of the flowing ice gouged and scraped the land, leaving in some areas scratches, called striations, in the bedrock. In other areas streamlined, elongate hills called drumlins were formed. Wisconsin's State capitol sits atop one of these hills. Impressive clusters of them are found in the Campbellsport Drumlins Unit of the Ice Age National Scientific Reserve and in other areas, particularly southeastern Wisconsin. The striations and the long axis of the drumlins indicate the direction the ice flowed. Streams, such as the Kickapoo River and Billings Creek, and Cheyenne Creek in Wildcat Mountain State Park, have carved winding, steep-sided valleys out of the rock. The Driftless Area is the only part of Wisconsin with no natural lakes.
In striking contrast to both of these glacial landscapes stands the dry upland of southwestern Wisconsin known as the Driftless Area. Much of this region is a rolling upland plain, with no glacial sediment that has been deeply cut by streams into a maze of narrow, twisting ridges and valleys. There are few natural lakes, bogs, or marshes in this part of the State. Several prominent mounds, such as Blue Mound in eastern Iowa County, stand as erosion remnants well above the surrounding plain. This Driftless Area landscape has been forming for many thousands of years, whereas our most recent glacial landscape is but 15,000 years old or younger.

The upper midwest "Driftless Zone"

(Also known as " Driftless Area" or "Unglaciated Area")

The "Driftless Area" of the Upper Midwest derives its name from the fact that it was unglaciated during the most recent glacial event about 12,000 years ago. Glaciers surrounded but did not pass over this land.

Portions of Iowa, Wisconsin, Minnesota and Illinois contain unusual geology. This karst region, also referred to as the Driftless Area, the Coulee Region or the Driftless Zone, escaped the last glaciers leaving the Paleozoic-age bedrock subject to erosion which helped create a curious topography of steep slopes and cliffs.

The Driftless Zone is an area of about 20,000 square miles in western Wisconsin, northeastern Iowa, southeastern Minnesota, and extreme northwestern Illinois, which was by-passed by the continental glaciers. As a result, the topography is more rugged than that usually associated with the Midwest. In Wisconsin, the Driftless Zone parallels the Mississippi River to the Illinois state line in a band 60 to 80 miles wide. About halfway a lobe extends farther northeast into Wisconsin. In Iowa, it also parallels the Mississippi River from the Minnesota state line to about Dubuque in a band approximately 20 miles wide.The Minnesota and Illinois portions are much smaller, by comparison, and much more irregularly defined.

In addition to the curious topography of steep slopes and cliffs, there are unique habitats, the algific (cold air) talus (loose rock) slopes. These slopes remain cool throughout the year and are home to rare species of plants and animals.

These slopes are usually north facing, are covered with a talus layer that allows ice-cooled air to exit from underground cracks and fissures. Upland sinkholes contribute to the air flow regime and are an important component of a unique system called an algific talus slope, meaning a cold producing rocky slope. Even when the outside air temperature is 90 °F (32 °C), ground temperatures on these slopes range from close to freezing (32 °F, or 0 °C) to about 55 °F (13 °C). Although the slopes will freeze in winter, the temperatures are moderated. These slopes remain cool throughout the year and are home to rare species of plants and animals.

The area known as the "driftless area" is notable as the further most edge of the glaciers' advance. Where the towering walls of ice stopped and then receded, the rock formations were formed.

As the ice moved, it froze around grains of sand, pebbles, and boulders, picked them up, and carried them along. The material frozen into the base of the flowing ice gouged and scraped the land, leaving in some areas scratches, called striations, in the bedrock. In other areas streamlined, elongate hills called drumlins were formed. Wisconsin's State capitol sits atop one of these hills. Impressive clusters of them are found in the Campbellsport Drumlins Unit of the Ice Age National Scientific Reserve and in other areas, particularly southeastern Wisconsin. The striations and the long axis of the drumlins indicate the direction the ice flowed.

Streams, such as the Kickapoo River and Billings Creek, and Cheyenne Creek in Wildcat Mountain State Park, have carved winding, steep-sided valleys out of the rock. The Driftless Area is the only part of Wisconsin with no natural lakes.

In striking contrast to both of these glacial landscapes stands the dry upland of southwestern Wisconsin known as the Driftless Area. Much of this region is a rolling upland plain, with no glacial sediment that has been deeply cut by streams into a maze of narrow, twisting ridges and valleys. There are few natural lakes, bogs, or marshes in this part of the State. Several prominent mounds, such as Blue Mound in eastern Iowa County, stand as erosion remnants well above the surrounding plain. This Driftless Area landscape has been forming for many thousands of years, whereas our most recent glacial landscape is but 15,000 years old or younger.