Temporal descriptions and speculation in rock art depart in two dimensions: How Old Is It? And: Where does It Fit in the Sequence of Changing Times?
Because few rock art glyphs, panels, or sites can be securely dated, researchers adopt various time-blocks, ages, and transitions inherited from archaeology, geology, or art history. Archaic, Holocene, Bronze Age, for example.
Happily, in the last dozen years a new and useful descriptor has emerged: Anthropocene. Does this term, with its own conceptual dimension and still hotly debated, clarify or muddy the temporal waters? Briefly, Anthropocene is the period during which human activity has affected the measureable stratigraphy of the geologic record. Some say, that’s 1950, others it’s the industrial age, or, arguably, the transition from hunter-gathers to agricultural complexes, say 10,000 years ago.
Anthropocene sharpens awareness about human impact and duration. Is it possible the oldest rock art has been in place longer than the time the human species may have remaining on this planet? A mind-opening sequence.
More. An engaging 2012 summary by two geologists - Is the Anthropocene an issue of stratigraphy or pop culture? - can be downloaded as a pdf.
Petroglyphs at Cascadia Cave, Oregon, a scientifically dated 8,000 year old heritage site.