Methods dating rock art
As soon as patina is removed, bacteria start to create patina again on the new surface.
When the art is not in direct physical contact, it is still possible to extract a relative age sequence for petroglyphs through differential development of rock varnish layers.
The most common and most reliable relative dating method is superimposition of one motif over another.
Stone is not directly datable in the time frame of human history. It is created by bacteria living on the rock and attaching clay particles to the rock.
In the process they incorporate the element manganese, which gives a dark color.
Rock Art, as we use the term here, refers mostly to pictures or symbols left on rock surfaces by members of traditional cultures.