a negative hand in a cave in Borneo was dated to 27,000 years by U/Th whereas its C age was only 8–10,000 cal BP; Plagnes et al., 2003).Due to these two contradictory sources of error, the dates given by the U/Th method may prove to be younger or older, with deviations that are much larger than the standard deviations given by laboratories.
However, in the case of engravings and red paintings, only indirect methods can be used that allow us to date deposits that have covered the works over time (TL, U/Th, oxalates, etc.).
As a result it is nearly impossible and very dangerous to base archaeological reasoning on U/Th ages of Palaeolithic artworks, so long as the dates are not confirmed by an independent method, dating the carbonates in the same samples by C being the best means of detecting anomalies.
The application of the U/Th method for the dating of prehistoric rock art is still experimental.
The conditions under which calcite forms depend largely on the hydrologic activity, which has greatly varied over the course of the Upper Palaeolithic and Holocene.
In many cases, we can see that the growth of speleothems stopped during much of the Upper Palaeolithic.Technical improvements (for less damageable sampling) and fundamental research on the causes of errors are needed.