The prominent mound in the center of northern Wisconsin is part of the Canadian Shield, which is made of the oldest rocks on the continent. The rocks were pushed up as ancient mountains were formed, eroded, and reformed. After the final uplift, about 200 million years ago, the northern highlands remained above water as an ancient sea covered the rest of the state.
Today, the northern highlands area of Wisconsin is widely known for its forests, lakes, and wetlands. Most of these lakes and wetlands occupy kettles in broad plains deposited by rivers carrying meltwater and sediment, called outwash, from the Langlade, Wisconsin Valley, and Chippewa Lobes of the Laurentide Ice Sheet as it receded from its maximum extent about 18,000 years ago.
The area contains the highest point in Wisconsin: Timms Hill, a thick accumulation of glacial debris, in Price County (elevation approximately 1,952 feet above sea level).