Jennifer - I'm not surprised - alot of the soils around here are heavy clay! If you really want to know the soil type in a certain area, you can go to McHenry County Soil and Water Conservation District's office in Woodstock - they can show you on their computer - it is so cool! They can show you water tables and all sorts of stuff. Their website is:
http://www.mchenryswcd.org/ . To rectify heavy clay soil in a garden, you have to add compost and other organic material. Have fun!