The championship tee on the third hole is an esker.
Eskers are sinuous ridges formed from drift deposited in tunnels running through a glacier.
"The area area is called kettle moraine and it was formed where two glacial lobes met. The complex collection of landforms and sediment got its name from its abundant round-bottomed depressions, which formed where blocks of ice were buried by outwash or other types of sediment. When the buried ice melted, the overlying sediment collapsed to form a pit resembling the widely used cast-iron kettles of the 1800's."
from Roadside Geology of Wisconsin Robert H. Dott
Wisconsin has an interesting geological history.