Grand Portage State Park
| Grand Portage State Park | |
| Minnesota State Park | |
 High Falls of the Pigeon River in Grand Portage State Park
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| Country | United States |
|---|---|
| State | Minnesota |
| County | Cook |
| Location | Grand Portage |
| - elevation | 846 ft (258 m) |
| - coordinates | 48°0′37″N 89°36′43″W / 48.01028°N 89.61194°WCoordinates: 48°0′37″N 89°36′43″W / 48.01028°N 89.61194°W |
| Area | 278 acres (113 ha) |
| Founded | 1989 |
| Management | Minnesota Department of Natural Resources, Grand Portage Indian Reservation |
  Location of Grand Portage State Park in Minnesota
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Grand Portage State Park is a state park at the northeastern tip of Minnesota, USA, on the Canada–United States border. It contains a 120-foot (37 m) waterfall, the tallest in the state (though it is on the border with Canada and thus partially in Ontario), on the Pigeon River. The High Falls and other waterfalls and rapids upstream necessitated a historically important portage on a fur trade route between the Great Lakes and inland Canada. This 8.5-mile (13.7 km) path plus the site of forts on either end are preserved in nearby Grand Portage National Monument. The state park, held by the surrounding Grand Portage Indian Reservation and leased to the state of Minnesota for $1 a year, is the only U.S. state park jointly managed by a state and a Native American band. It is also the only Minnesota state park not owned by the state.
During the Paleoproterozoic era from 2.2 to 1.9 billion years ago, mud and muddy sand accumulated on the bed of a shallow sea. These sediments compacted into layers of shale and graywacke. Dubbed the Rove Formation, they are among the oldest unmetamorphosed sedimentary rock on earth. 1.1 billion years ago the North American Plate began to crack in the middle, and lava flowed out of this Midcontinent Rift System creating the distinctive basalt of Lake Superior's North Shore (and Interstate Park to the south). In what is now Grand Portage State Park, upwelling magma did not reach the surface but intruded into fractures in the Rove Formation, cooling more slowly into diabase rather than basalt. One set of intrusions formed northeast-to-southwest trending sills while a later event formed northwest-to-southeast trending dikes. Together they are known as the Logan Intrusions after Canadian geologist William Edmond Logan.
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