Views Read Edit View history. Dating an object from the early 20th century hence gives an apparent date older than the true date. Subsequently, a sample from the fossil forest was used in an interlaboratory test, with results provided by over 70 laboratories. Circular Reasoning or Reliable Tools? The calculations to be performed on the measurements taken depend on the technology used, since beta counters measure the sample's radioactivity whereas AMS determines the ratio of the three different carbon isotopes in the sample. These methods can be used to date the age of a sediment layer, as layers deposited on top would prevent the grains from being "bleached" and reset by sunlight.