As explorers began traversing the northern Great Plains in the mid-19th century, they noted odd sightings on their journeys west ─ enormous mounds of elk antlers stacked along rivers in North Dakota, South Dakota, Wyoming and Montana. In his journal, Prince Maximilian zu Wied described one such pyramid druing his expedition’s through the American West l in the 1830s. Dubbed the Elkhorn Steeple, the mound stood roughly 18 feet high and 15 feet in diameter at its base and contained well over 1,000 antlers—so many that the pile sank several inches into the ground from the weight. Hunting and war parties of Blackfeet were said to have built-up the stack over the course of centuries, adding a layer of each time they passed the mound and sometimes marking the size of their party with red lines along the antler.
Some of these antler assemblages also contained deer, wolf, bison and mountain sheep skulls and bones, most measuring anywhere from 12- to 20-feet high and 10- to 15-feet in diameter. There are many theories about their reason for being, from religious and ceremonial purposes to a boney cairn marking hunting grounds and less-traveled trails.