The Picture Rock Pass petroglyphs are carved on a south-facing basalt boulder near the summit of the pass. No one knows when the Picture Rock Pass petroglyphs were created or who carved them. However, they were probably created during either Clovis Period (10,000 and 12,000 years ago) or the Stemmed Point Period that followed (7,500 to 10,000 years ago), placing the likely period of the rock carvings sometime between 7,500 and 12,000 years ago.