[sammyg2]

Ah, the cave of Lascaux.
They really do not not know how old those drawings are, they think they MIGHT be as old as 30,000 but they can't prove it and they admit it. They are GUESSING. I suggest these paintings are only about 6000 years old.
This is taken from their official website:

The range of methods and tools used to date the cave art is somewhat limited, partly because the figures are not in a position favourable to stratigraphic dating most of the time and also because of the nature of the materials used. In the eventuality of a single period of Palaeolithic occupation of the site as at Fontanet (Ariège), Combarelles or Rouffingnac (Dordogne), and to some extent, at Lascaux, it is reasonable to note the contemporaneousness of the wall paintings and the material found on the floor of the cave. Whether lithic or bone, or in the form of products of combustion, these elements are more easily dated.

An identical approach applies to the pigment which had fallen to the ground during the painting or drawing. They have been sealed in the archaeological levels, at the foot of the decorated walls and are therefore contemporary with the datable archaeological artefacts, and can be dated using radiometry (bone, carbon) or possibly typology (lithic or bone industry). During the past few decades several attempts have been made at direct dating of the paintings using the radiocarbon method (J. Clottes and M. Lorblanchet). The ever-improving performance of radioactive measuring instruments today allows analyses to be made of matter weighing only a few milligrams. Nevertheless, only the paintings and drawings which incorporate charcoal can be studied in this way; in most of the Perigord caves, as at Lascaux, typing of the pigment shows that the basis of the material used on all the figures is metal oxides, iron or manganese, materials that are impossible to date using the suggested methods.