fill, forming the Great Lakes. The shoreline at its maximum reached over 500 feet (150 m) above its current height, and at its minimum fell to 250 feet (75 m) below its current level. When the levels of Lake Michigan and Lake Huron fell 2,000 years ago, it created rapids at Sault Sainte Marie, which restricted the release of water from Lake Superior and brought the shoreline to its present level. The modern shoreline is composed of basalt lava flows. In the south, near Duluth, other materials, such as slate, greywacke and sandstone, are found a short distance inland; but in the north, the entire bedrock made of basalt and gabbro is exposed in patches miles from shore. When the bedrock hits the surface of the lake at a shallow enough angle, the beach is covered with washed up rocks. When it hits the lake at a steep angle, it breaks off and makes sharp cliffs ending at the lake. Attractions Minnesota Duluth Highway 61 and the North Shore Scenic Drive Glensheen Mansion Two Harbors Superior National Forest Superior Hiking Trail Silver Bay Schroeder Tofte (home of the North Shore Commercial Fishing Museum) North Country Trail Grand Marais Gunflint Trail Lutsen Mountains ski resorts State parks and national monument To people who camp in the state parks along Minnesota's North Shore, the term North Shore refers to both the shore of the lake and all the rivers which run into the lake. Thus there are numerous "North Shore state parks," most of which are not actually on the lakeshore, and several of which are not even particularly close to it. Jay Cooke State Park is on the Saint Louis River, which enters into Lake Superior through the Duluth harbor several miles away. Gooseberry Falls State Park has campgrounds fairly close to Lake Superior, but its main attractions are the five falls on the Gooseberry River and the Gitchi Gummi Trail, which overlooks the north face of the river gorge. Split Rock Lighthouse State Park is popular for its historic Split Rock Lighthouse. Since the lighthouse is separately run by the Minnesota Historical Society, there is a separate fee for admittance. Tettegouche State Park lies at the base of the Baptism River and is famous for the high cliffs overlooking Lake Superior. Palisade Head, the highest cliff in Minnesota, is accessible outside the main entrance to the state park, although a