Image courtesy NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Adam Voiland.

In most American states, the Turtle Mountains—which rise 600 to 800 feet (180 to 240 meters) above the surrounding plain—would be called hills. But in North Dakota, one of the flattest states, people have a habit of calling even relatively modest rises mountains. (In the past, the U.S. Board of Geographic Names argued that mountains should have at least 1,000 feet (300 meters) of local relief to earn the designation, but the group abandoned the argument for linguistic consistency in the 1970s.)

Whether hills or mountains, the hummocky highlands that straddle the border between North Dakota and southern Manitoba have enough elevation that they receive significantly more precipitation than the surrounding plains. As shown by this image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite, enough moisture collects on the hills to support forests. The surrounding lowlands are a patchwork of grasslands and farms. In the lower image, a detailed view of a largely undeveloped part of Turtle Mountain Provincial Park, hundreds of ponds and lakes pockmark the landscape. A few roads and oil wells also appear. Read more