Millions of years ago, Trempealeau Mountain, the bluffs of Perrot State Park, and the Minnesota upland across the river formed one continuous rock mass. Over time, Cedar Creek, Big Trout Creek, and their tributaries carved channels that isolated Trempealeau Mountain, while the Mississippi River ran north of the park. During the last part of the Ice Age, some 50,000 years ago, glacial meltwaters laden with sand, gravel, and debris blocked the river's previous route and forced the Mississippi River to seek a new channel, shifting the boundary between Wisconsin and Minnesota and giving Wisconsin Perrot State Park.