Petroglyph Canyon, a four-mile canyon on the Montana-Wyoming border, is an important archaeological site noted for an eight-hundred-foot concentration of prehistoric rock carvings. At least eighteen groups of petroglyphs appear on canyon walls and boulders, along with hearths and stone flakes from toolmaking. The imagery includes human figures, bison, bighorn sheep, and some explicit sexual scenes, mostly made by pecking into darkened sandstone. The canyon is especially significant for the variety of its artwork, the relatively limited erosion that has preserved it, and stylistic links to distant rock art sites that may help trace past movement and cultural connections among the peoples who created it.