If you live in Michigan your soils were probably formed from glaciers, otherwise known as glacial till.Go to your local Natural Resources Conservation Service center, and they can print a map with the soils listed, and give you a description of the soil. Find your NRCS phone number here: http://offices.sc.egov.usda.gov/locator/app?service=page/CountyMap&state=MI1&stateName=Lower%20Mich igan&stateCode=26

Be sure to get the soiltested soon!