Prehistoric North Dakota

From Frozen Sea to Grassland Sea

North Dakota remains as flat as it probably was when it was still covered with ancient seas. Put a brick under the bottom left corner of a sheet of plywood, and you will have some idea of what North Dakota is like. It is not perfectly flat, however, thanks largely to Ice Age glaciers.

The state’s most populated region is the fertile Red River Valley, the bed of an Ice Age lake that runs along the North Dakota-Minnesota border. North Dakota’s only large natural lake is Devils Lake, in northeast North Dakota. To the west is the Drift Prairie Region, a glaciated region of rolling hills and rich soils. Grasses are tall or short, depending on the availability of moisture.

Depressions carved by Ice Age glaciers left thousands of small lakes, sloughs and potholes scattered across North Dakota. Many of these wetlands dried up naturally, while people drained others. But thousands of “prairie potholes” remain, making North Dakota one of the most important states in terms of waterfowl habitat. Few states boast more wildlife refuges, some scarcely larger than a pothole.

Glaciers never covered North Dakota’s southwest corner, which is separated from the rest of the state by the Missouri River. This is a drier, more rugged land of short grasses, buttes, bluffs, breaks and badlands. Along the Little Missouri River, the land has eroded to form the Little Missouri Badlands. This is the home of Theodore Roosevelt National Park, named for our most adventurous president, who ranched in the area.

If you scraped away North Dakota’s grasslands, you’d discover that much of the state is buried under boulders or dust left by glaciers. Over thousands of years, much of this glacial dust evolved into the soils that make North Dakota one of the most agricultural states. The state motto is “Strength from the Soil.”

Mixed in with North Dakota’s soils and glacial debris are fossils of Ice Age plants and animals, including beaver, caribou, and mammoths. Today most caribou live north of North Dakota, while mammoths are extinct. Bison bones commonly found in North Dakota stream banks range from thousands of years old to a few hundred, linking the present with the Ice Age.