Radiocarbon dating is one such type of radiometric dating. As soon as a living organism dies, it stops taking in new carbon.The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy.
However, the principle of carbon-14 dating applies to other isotopes as well.
The object's approximate age can then be figured out using the known rate of decay of the isotope.
For organic materials, the comparison is between the current ratio of a radioactive isotope to a stable isotope of the same element and the known ratio of the two isotopes in living organisms.
For the trenches, dugouts and tunnels—many containing human remains and personal belongings—are ethical minefields too.
In a paper in this month's , Nicholas Saunders, an anthropologist at University College, London, says that archaeologists on these battlefields face a concentration of all the issues that have concerned archaeology in the past ten to 15 years.