In 1978 two Waco arrowhead hunters found a bone in a ravine. It turned out to belong to a Columbian mammoth that had perished there about 68,000 years ago. Now open to the public after over 30 years of excavation, the site features the nation's only recorded discovery of a herd of Pleistocene mammoths that includes young ones. In 2015 it was added to the National Park System, which has brought added funding and prominence.
It's generally thought that the herd was trapped and drowned by fast-rising floodwaters of the Bosque River.
