Indian Lake Park lies at the edge of the unglaciated or driftless area of southwestern Wisconsin, where both glaciated and unglaciated landforms are prominent. Steep slopes of exposed rock show that this valley was never completely covered with ice, yet large boulders in the draws and on the valley floor were brought here by a finger of ice that fanned out from the main body of the glacier. Indian Lake is one of many shallow kettle lakes in the area, created when the glacier retreated, and the outwash plain by the lake formed when glacial meltwater carried large quantities of silt and sand into the valley. Plant life here is very diverse: the cool north-facing slope along the lake is dominated by paper birch, while ancient gnarled oaks on the hilltops are being crowded by younger hardwoods. Abundant brambles and aspens show that logging and grazing once took place in the woods. For several hundred years Indians camped at the southwest end of the lake. During that period, the slopes on the hills above were quite open and covered with prairie grasses and wildflowers, and frequent fast-moving prairie fires helped keep these areas free of trees. When settlers stopped the fires, trees began to fill in the open spaces, and today only a few small patches of prairie remain on the very dry southwest-facing slopes.