 More than 4,000 pictures of animals, humans, natural life experiences, hunting, and dancing were carved over a span of thousands of years.Most of the petroglyphs are on large cliffs, divided among multiple ancient residences, and in some cases they have been carved over older images.The first carvings depicted natural human and animal figures, often irregularly, but over time they began to more closely resemble the measurements and proportions of their subjects, including such details as the foot muscles of people in hunting scenes.