The North Dakota Badlands were named for the difficulty of traveling across them before modern roads were built. Part of the Northern Great Plains, the area has been carved by rain, wind, and the running water of the Little Missouri River. Its layers of sand, silt, clay, and lignite coal were deposited by river, lake, and swamp systems during the Paleocene Age, about 55 million years ago. The land still undergoes change with each storm.