1. A type of clay soil formed by the weathering of glacial drift, typically found in the Midwest and characterized by poor drainage and sticky texture when wet.
Usage: geology; regional (U.S. Midwest)

Examples

• The farmer struggled to work the gumbotil soil in spring when it was saturated with moisture.
• Gumbotil deposits are common in Iowa and Illinois, where glaciers once covered the landscape.
• The sticky gumbotil made it difficult to drive across the field after heavy rain.
• Geologists identified the gumbotil layer as evidence of ancient weathering processes.