Butler Lake formed about 10,000 years ago when great Ice Age glaciers melted, creating one of many ice block lakes, or kettles, along the margins of the receding Green Bay and Lake Michigan ice lobes. Stranded blocks of ice sometimes became buried by sediments washed out from melting glaciers, and when the ice blocks melted, the sediments slumped to form depressions called kettles. Kettles that contain water are often called kettle ponds or kettle lakes, and they appear in a variety of shapes and sizes depending on the dimensions and positions of the corresponding ice blocks. Below the local water table, ground water seeps into the kettles to create ponds and lakes.