Wild River State Park is a state park of Minnesota, United States, curving along 18mi of the St. Croix River. This long, narrow park is shaped somewhat like a sideways 'S', with development largely concentrated in the lower third. The remote upper sections flank the mouth of a tributary called the Sunrise River. The park is managed to provide quieter, more nature-oriented recreation as a counterpoint to the busier William O'Brien and Interstate State Parks downstream.Wild River State Park is named after the St. Croix's designation as a National Wild and Scenic River. The park contains the Point Douglas to Superior Military Road: Deer Creek Section, a surviving section of the Point Douglas to Superior Military Road built in 1853, which is listed on the National Register of Historic Places.Natural historyGeologyThe bedrock of the park is basalt formed by volcanic activity 1.1 billion years ago. This is overlain by a thick layer of glacial debris. During the Wisconsin glaciation 16,000 years ago, a small glacial lobe branched northeast off the Des Moines Lobe, blocking drainage from farther north. Water backed up into Glacial Lake Grantsburg. The soil in the park is quite sandy from the sediments that accumulated in this now-vanished lake. At the end of this ice age 10,000 years ago, meltwater flowing out of Glacial Lake Duluth carved the St. Croix River Valley. Today the river is one hundred times smaller than its glacial maximum. The ancient bank of the river is a bluff running through the park, well back from the current riverbed.
