Blackwell Forest Preserve

Visitors hiking through Blackwell Forest Preserve in Warrenville walk on land that the retreating Wisconsin Glacier shaped 12,000 to 15,000 years ago. In fact, the glacier’s meltwaters left behind much of the soil that covers DuPage County today. After the glacier’s retreat, savannas with widely spaced oak trees formed on the higher ground while the lower-lying ground became home to marsh and prairie plants.