Lewis and Clark, among others, reported that American plains Indians occasionally precipitated success in buffalo hunts in a literal way by driving the animals over cliffs. However, a dispute has simmered for some time whether the bison bones littering one site near Crawford, Nebraska, are the doing of hunters taking advantage of steep drop, or a natural event. The Rocky Mountain News's Jim Erickson reviews the arguments on both sides. The primary aspect that makes the case interesting is the age of the bones, about 10,000 years. If hunters did it, it would be perhaps the oldest known buffalo jump killing site in North America. Most, it says here, date to about half that age.