Door County’s northern interior was shaped by glaciers that scoured the northern Door Peninsula down to its dolomite limestone bedrock, leaving a highland region without the deep soils found on the southern peninsula. As the ice melted, rivers flowed along old bedrock riverbeds into Lake Michigan, creating wide mouths that became rich wetlands and coves such as Baileys Harbor, North Bay, and Rowleys Bay. Retreating glaciers also left drumlins, the tear-drop shaped hills seen in the Liberty Grove Drumlin Field. The limestone landscape preserves fossils of corals, crinoids, and other creatures from ancient seas, and abandoned lime kilns and stone fences remain scattered across Door County. Heated in simple kilns, limestone produced quick lime used for mortar and whitewash. Although thin soil over dolomite bedrock makes farming difficult, orchards thrive in the peninsula’s mild, moist lake air.