Evidence of glaciation is everywhere in Michigan
Save the date! To learn more about how glaciers helped to form Michigan’s soils and landscape features.
This article describes how glaciers once moved across the Midwest. To learn more about the resulting landforms, sediments and soils that comprise the present Michigan landscape, consider attending the workshop titled, “Forest Soils and Glacial History: Michigan’s Complex Web”, scheduled for March 6, 2015 at the Boardman River Nature Center, 1450 Cass Road, Traverse City. The workshop is hosted by Kama Ross of the Leelanau/Grand Traverse/Benzie Conservation Districts and features Dr. Randy Schaetzl, Professor of Geography and Geology at Michigan State University. Contact Kama Ross to register.
Imagine this, Michigan buried under up to one mile of ice. This scene is not referring to the polar vortex of winter 2013-14, but rather to the glaciers that covered Michigan and the entire Midwest more than 10,000 years ago. These glaciers are referred to as continental glaciers, because they slowly moved across large areas of an entire continent; in this case North America. These are different from alpine glaciers, which form at the tops of mountains and move downhill to create ‘U’ shaped valleys and sharp peaks. Landscapes like Yosemite were formed by alpine glaciers. In contrast, the Michigan landscape was formed by continental glaciers.
During glacial periods, snow accumulates up to thousands of feet thick. The bottom parts of these snow piles turn to ice, and flow as glaciers. The glaciers that covered Michigan were thought to be up to a mile thick. Gravity, along with the pressure from the weight, causes the glacier to creep across the landscape.
Glaciers are efficient at erosion of bedrock, which was a widespread process across much of southern Canada. This rock and soil was eventually dragged to the southern Great Lakes region and deposited here as glacial sediment. Sediment is deposited by the glacier when movement stalls or when the glacier begins the melting process.
Because of their size, glaciers may take hundreds of years to melt. During the process, the front of the glacier will stall, depositing large amounts of material along the stalled front. Large glacial lakes can also form in front of the glacier as the ice sheet acts as a dam to trap the melt water. Wide river valleys form when the ice dams shift allowing the meltwater to flow. Evidence of all these actions can be seen today, across Michigan as landforms and forest types, if your eye is trained to see it!
Learn more about how to recognize the glacial evidence at the Workshop on March 6, 2015. If you are unable to attend the workshop, stay tuned! A second article from Michigan State University Extension will relate Michigan’s current landforms and soils to the glacial process.