These people knew how to make lethal weapons. They let spear points, knife blades and other tools scattered all across the plains. And they spread fast. The evidence suggests it took them only 1,000 years to spread across the entire northern continent. 

 

What can we learn today about the lifestyle of these butchers of the plains? They left a stream of clues to how they lived, including strange pyramids of rocks. Inside are bones of animals that show how they were slaughtered and cut up for meat. These cares are thought to be cold-weather larders, marking prehistoric hunting camps. When hunting parties had more meat than they could eat or carry, they would stash the surplus under these rocks to be collected later. They seemed to have used bones as markers.