A kame, a gravel hill formed 70,000 years ago by a melting glacier thicker than the Willis Tower is tall, was created as streams flowed through channels in the ice, broke apart rock carried within the glacier, and deposited it as smooth cobble. Covering only 11 of Blackwell Forest Preserve's 1,300 acres, it holds remarkable biological richness, with more than 270 different kinds of plants growing there, making it one of the county's most diverse natural areas. Forest Preserve District ecologists and volunteers are working to restore this natural wonder to its full potential.