Petroglyph Canyon is located in Montana

Petroglyph Canyon (24CB601) is an archaeologically significant canyon in the northwestern United States. Located on both sides of the border between Montana and Wyoming, the canyon has long been obscure due to its small size. However, it gained substantial attention in the late 20th century because of its numerous prehistoric petroglyphs, and much of it was named a historic site in the 1970s.

• http://en.wikipedia.org/wiki/Petroglyph Canyon