The bones were buried under and are therefore older a layer of ash that resulted from a volcanic eruption dating back to years BP Before Present; "present" indicates c. A disadvantage to this technique is that in order to get accurate results, the sediment to be tested cannot be exposed to light which would reset the "clock"making sampling difficult. Most are multidisciplinary, but some are limited, due to their nature, to a single discipline. The technique has potential applications for detailing the thermal history of a deposit. These radionuclides—possibly produced by the explosion of a supernova—are extinct today, but their decay products can be detected in very old material, such as that which constitutes meteorites.
Before the advent of absolute dating methods, nearly all dating was relative.
This means that the flux of cosmic rays impinging on the atmosphere varies, and therefore so does the 14 C production rate. By measuring the amount of carbon remaining, scientists can pinpoint the exact date of the organism's death. With relative dating, we can see that artefact A came after artefact B by examining its evolution in design or methods of production. Earth 's atmosphere is constantly bombarded with cosmic rays from outer space. Pottery Experts I found a piece of pottery on the beach in Nova Scotia.