Question

Name and clearly describe one technique for determining the age of fossils in geological context. Are there any contexts in which this technique would not work? (minimum of 300 words)

Answer 1

• Radio carbon dating is a technique used to describe the age of fossils.
• In this technique , the amount of C14 present in the sample can be calculated with reference to standards.
• C14 carbon takes time to decay . Its half life 5730 years.
• If the ratio of C14 : C12 at the time of death and the present ratio of C14 are known , then the age of the organism can be calculated.
• Normally if the organism is alive the C14 present in the organism enters the carbon cycle and gets converted to Nitrogen by the process of photosynthesis by plants.
• When the animal dies , the carbon does not enter the carbon cycle and starts to decay.
• The carbon acquired by the organism should be from the atmosphere and it should not be acquired from any other sources like limestone.
• The radio carbon dating is performed only on organisms that acquired carbon from the atmosphere .

Process

• The bone of the fossil is cleaned and small sample is thoroughly ground to pieces.
• After this a weak acid is added to remove the outer covering .
• After this gelatinisation process is carried out to remove the bone protein.
• Then the sample is freeze dried to remove excess water.
• The carbon present in the sample is converted into benzene.
• After this a scintillator chemical is added to benzene. This chemical detects the decay and glows as flash of light when a decay is present.
• The flash of light is recorded by spectrometer which is analysed by a software and the radio carbon data will be provided.

This technique would not work

• When the carbon in the sample is from other source and not from atmosphere.
• If there is contamination with present day carbon .