Michigan Geology 101

This interactive map displays information related to Michigan's geology, natural features, and mining history. Within the map, users can view the distribution of sediments that were deposited and features left behind by the continental ice sheets that moved across Michigan during the last Ice Age, as well as sediments deposited by wind and water since the glaciers melted. These are shown in the layers titled Michigan  Surficial Geology ,  Critical Dunes  and  Quaternary  Geological Features. In addition, you can view the bedrock geologic formations that lie directly beneath the glacial sediments by turning on the Michigan Bedrock Geology layer. You can also explore where copper, gold and iron were historically mined in Michigan. Native Americans mined copper in Michigan's Upper Peninsula for thousands of years. Native people used copper to fashion tools and ornaments and revered it as a source of power. 

The geology of Michigan spans nearly four billion years of Earth history, and while much of the state’s rock riches are hidden from view by vegetation and freshwater lakes, beneath the landscape is a story of volcanic activity, ancient saltwater seas teeming with life and miles-thick continental glaciers.

The oldest rocks in Michigan occur at or very near the surface in the western Upper Peninsula. These rocks consist of igneous, metamorphic and sedimentary rocks from Precambrian time and represent some of Earth’s original continental crust. In the Lower Peninsula and eastern Upper Peninsula, these Precambrian rocks are buried by a thick sequence of Paleozoic sedimentary rocks that were deposited during a time when the region that is now Michigan was near the equator and was covered by a shallow sea that dried up periodically. Much more recently, at various times during the Pleistocene Epoch, Michigan was covered by thick continental ice sheets. As these glaciers expanded and retreated across the landscape, they eroded the bedrock beneath them, softer rocks such as shales eroding more easily than harder rocks like sandstone and limestone. This contributed to the formation of the Great Lake basins. As the ice sheets from the last glacial period finally melted away completely from Michigan around 11,000 to 9,000 years ago, not only did they create the Great Lakes, but they left behind thick deposits of unconsolidated boulders, cobbles, pebbles, sand, silt and clay that cover most of the state, with some notable exceptions.

 Michigan’s geologic materials (bedrock and glacial deposits) are an important source for a diversity of natural resources that we rely on every day, from the water that we drink to the industrial materials that fuel our economy and maintain our infrastructure. The work by geologists to map and interpret the surface and subsurface geology is necessary for locating critical resources for our society and planning for the wise use and management of those resources. Furthermore, by analyzing Earth’s geologic past, geologists and other scientists can make important predictions about how the planet will evolve into the future and how humans are impacting the planet.