North Dakota’s landforms rise in steps from east to west. The Red River Valley along the Minnesota border is the flat floor of a vanished glacial lake and holds the state’s lowest point, the Red River at Pembina, 229 m (750 ft) above sea level. West of it the Drift Prairie and the Missouri Coteau are glacial country of rolling hills and thousands of pothole wetlands, with the Turtle Mountains rising on the Manitoba border. Beyond the Missouri River the unglaciated Great Plains take over, cut in the southwest by the Little Missouri Badlands, where White Butte reaches 1,069 m (3,506 ft), the state’s highest point. Across 183,123 km² (70,704 sq mi), five named features tell most of that story: a butte, a badlands river, a reservoir, a lake with no outlet and a valley that is not really a valley.
White Butte, 1,069 metres above Slope County
North Dakota’s summit is not a mountain but a butte, a flat-topped remnant of rock left standing as the land around it wore away. White Butte rises in Slope County, about 10 km (6.5 mi) south of Amidon and 5 km (3 mi) east of US 85, inside the boundary of the Little Missouri National Grassland. Its slopes are pale and heavily eroded, badlands-style, beneath a darker cap. It is about 56 km (35 mi) south of Theodore Roosevelt National Park and sits on private land owned by the Dennis family, who ask walkers for a small donation at the parking area; the round trip on the trail is about 6.4 km (4 mi).
The butte is a useful reminder of how modest the state’s relief is. The Killdeer Mountains, 121 km (75 mi) to the north, rise roughly 300 m (1,000 ft) above their foothills and look far more dramatic, yet their top is 69 m (225 ft) lower than White Butte. What makes White Butte the highest point is not local steepness but the general tilt of the state: the land climbs gradually westward from the Red River toward the Rockies, so a butte near the Montana border starts from a much higher base than anything in the east.
The Little Missouri Badlands and Theodore Roosevelt’s ranches
The Little Missouri River rises in northeastern Wyoming, near Devils Tower, and runs about 900 km (560 mi) through Montana and South Dakota before flowing north through western North Dakota to join the Missouri. Along its North Dakota course it has cut the state’s most striking landscape. The badlands here stretch for about 305 km (190 mi) and are 10 to 30 km (6 to 20 mi) wide, a maze of buttes, pyramids, domes and cones in browns, reds, greys and yellows.
The rocks are young by geological standards. Most beds along the river belong to the Bullion Creek and Sentinel Butte formations, siltstone, claystone, sandstone and lignite coal laid down on a coastal plain during the Paleocene, roughly 66 to 56 million years ago, while the Rockies were being raised to the west. Soft, barely consolidated layers like these erode fast when the few heavy rains of a dry climate fall on bare slopes, and the Little Missouri carries off that sediment in highly seasonal floods. Colour comes partly from the coal. In places lignite seams have caught fire and burned for years underground, baking the clay above them into bright pink and red rock. For how this style of erosion works elsewhere, see what badlands terrain is.
The badlands also shaped American conservation. Theodore Roosevelt first came in September 1883 to hunt bison and bought into the Maltese Cross Ranch south of Medora. After his mother and wife died on the same day, 14 February 1884, he returned and started a second ranch, the Elkhorn, 56 km (35 mi) north of Medora. He lost his cattle in the starvation winter of 1886–1887, and his western years fed into the conservation policies of his presidency. Theodore Roosevelt National Park now protects 285 km² (70,446 acres) in three units, the South Unit by Interstate 94 at Medora, the North Unit along US 85, about 130 km (80 mi) to the north, and the Elkhorn Ranch between them, all linked by the Little Missouri and the Maah Daah Hey Trail. It is the only US national park named after a single person.
Lake Sakakawea and the edge of the ice
The Missouri River crosses North Dakota in a deep trench, and that trench is also a boundary in time. East and north of it lies glaciated land; south and west, the ice never reached. Lake Sakakawea, the reservoir that now fills the trench, is described as marking the maximum southwestern extent of glaciation in the region.
The lake was created by Garrison Dam, an earth-fill embankment more than 3.2 km (2 mi) long built by the Army Corps of Engineers between 1947 and 1953 as part of the Pick-Sloan plan for flood control and hydropower. It is described as the fifth-largest earthen dam in the world, and the reservoir behind it, impounded from 1953, stretches northwest up the river valley through six counties as far as Williams County. Sakakawea is the largest artificial lake entirely within North Dakota and the third-largest reservoir in the United States by volume, after Lake Mead and Lake Powell. It is typically only 3 to 5 km (2 to 3 mi) wide, widening to 23 km (14 mi) at the Van Hook Arm, because it is a drowned river valley rather than a basin.
The flooding came at a cost. Between one-sixth and one-quarter of the Fort Berthold Indian Reservation’s land went under the water, including the agency town of Elbowoods and the original site of Sanish; residents of Van Hook were also forced out, although only a small part of that town site was ever flooded. About 1,700 members of the Three Affiliated Tribes were relocated, founding new towns such as New Town, White Shield and Mandaree. The Missouri River guide follows the rest of the river’s dam chain downstream.
East of the trench, the Missouri Coteau is the ice sheet’s signature. This plateau of Pierre Shale, covered by hard glacial deposits, is a hummocky country of low, rolling hills, grassland and potholes. The potholes formed when blocks of ice buried in the till melted and left depressions that fill each spring with snowmelt. They belong to the Prairie Pothole Region, which covers about 800,000 km² across three Canadian provinces and five states and is a key breeding ground for migrating waterfowl.
Devils Lake, a basin with no outlet
In the northeast, on the Drift Prairie, Devils Lake shows what glacial landscapes can do to people who build on them. It is the largest natural body of water in North Dakota and the terminus of a closed drainage basin of about 9,800 km² (3,800 sq mi). With no outlet, the lake loses water only to evaporation and seepage, so it is usually shallow and salty, and its level rises and falls with the weather over years and decades.
Above 441 m (1,447 ft) the lake spills into neighbouring Stump Lake, and at 444 m (1,458 ft) the combined lake would overflow into the Sheyenne River, a tributary of the Red, a level it has not reached in about 1,000 years. Heavy precipitation between 1993 and 1999 doubled the lake’s size, forcing more than 300 homes to move and flooding 28,000 hectares (70,000 acres) of farmland; on 27 June 2011 it reached an unofficial record of 443.3 m (1,454.3 ft). Draining wetlands for cropland across the basin has sped runoff into the lake. The Spirit Lake Tribe, whose reservation lies along the southern shore, has been hit hard. The name itself is a mistranslation of the Dakota for sacred or spirit water, the source of the names Spirit Lake and Minnewaukan.
North of Devils Lake the Drift Prairie ends against the Turtle Mountains, a wooded plateau about 600 m (2,000 ft) above sea level and 90 to 120 m (300 to 400 ft) above the plains, roughly 32 km (20 mi) north to south and 64 km (40 mi) east to west, straddling the Canadian border. Boundary Butte on its western edge is the state’s most prominent peak, rising 314 m (1,031 ft) above its surroundings.
The Red River Valley, floor of Lake Agassiz
The eastern edge of the state is its flattest ground. It is the bed of Lake Agassiz, a proglacial lake fed by meltwater from the retreating Laurentide Ice Sheet. At its greatest extent, around 13,000 years ago, the lake may have covered as much as 440,000 km², larger than any lake existing today and about the size of the Black Sea. It spread over eastern North Dakota, northern Minnesota, Manitoba, northwestern Ontario and Saskatchewan, and it was named in 1879 by Warren Upham after Louis Agassiz, the founder of glaciology. It eventually drained toward Hudson Bay, with its last major shift in drainage around 8,200 years ago, and left behind Lake Winnipeg and the fine lake-bottom sediments that make the valley very fertile farmland, planted to wheat, sugar beets and maize.
The Red River of the North, which forms most of the North Dakota–Minnesota border, is very young: it developed only after the lake drained from its valley, about 9,500 years ago. It runs about 885 km (550 mi) north to Lake Winnipeg, 635 km (395 mi) of it in the United States, and falls only about 1 m for every 5 km, roughly a foot per mile. Calling its basin a valley is a misnomer. The river has cut a channel only a few hundred feet wide; the broad plain around it is the old lake floor. With so little gradient, high water has nowhere to go but sideways, and because snow melts first in the warmer south while the northern reaches are still frozen, the flow backs up against ice. In 1997 that combination flooded Grand Forks, where 75% of the population was evacuated, and later prompted the Fargo–Moorhead Area Diversion Project. Each great flood briefly refills a little of Lake Agassiz.
Seen together, the five features trace a single gradient: badlands and buttes on the unglaciated west, a dammed river on the ice margin, potholes and a closed lake on glacial till, and a lake-bed plain in the east. The geography of North Dakota fills in the climate, rivers and towns on each step.