Much of this volcanic ash comes from the Great Basin, a geographic area within which the states of Utah and Nevada lie today.

Want to know the best Badlands National Park one day itinerary ... Ancient Hunters Overlook, Yellow Mounds Overlook, Conata Basin Overlook, Homestead Overlook, Burns Basin Overlook, Prairie ...

Of the remaining seven states, all but one is limited to a single park. South Dakota is the outlier; it has two parks. One of them is Badlands ... overlooks like Yellow Mounds and Pinnacles ...