Paintings on the cave walls were often done with
(A) carbon from burned woods, hence charcoal,
(B) or with natural earth pigments, such as mixture of clay and iron oxides, and these pigments are known as ochre; ochre ranged in colors from yellow, red and brown.
The natural color of ochre, depends on -
- if the iron oxide-hydroxides have been “hydrated”, and you get limonite, hence the pigment is referred to as yellow ochre,
- or if it is “anhydrous iron oxide”, you’d get hematite, red ochre,
- or if there are presence of certain amounts of manganese oxide in brown ochre in “partially hydrated” iron oxides, of which there are two varieties:
- sienna (less than 5% manganese oxide)
- umber
You can get reddish brown ochre by dehydrating, by heating natural sienna or umber, to get burnt sienna or burnt umber.
You would carbon date whatever pigments that are present in the paint. You wouldn’t date the cave itself, because that would only date the rocks of the caves.