Geology
Lake Shetek and the surrounding landscape of wetlands and rolling hills are the result of glaciation. The lake lies on the Altamont Moraine, a terminal moraine marking the farthest extent of an ice lobe during the Wisconsin glaciation. This most-recent glaciation deposited a very thick blanket of till over the area.
Lake Shetek began forming as the climate started to warm 15,000 years ago. Water from the melting glaciers carved channels into the moraine. Where one channel—now occupied by Beaver Creek—intersected the channel now occupied by the Des Moines River, a buildup of sediment and slumping banks partially dammed the outflow, creating a large, shallow lake.
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