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Which of the following is the relatively most accurate method for dating of fossils -
A
Electron-spin resonance method
B
Uranium-lead method
C
Potassium-argon method
D
Radio-carbon method
Detailed Solution
The age of fossils is determined by radiometric (radioactive) dating and other physical methods.
The radio-carbon ($^{14}C$) method is used for fossils up to about 50,000 years old; the potassium-argon and uranium-lead methods are used for very old rocks (millions to billions of years), where the errors in absolute terms are large.
The electron-spin resonance (ESR) method measures the number of trapped electrons accumulated in materials such as tooth enamel and shells due to natural radiation since burial.
According to the answer key of this paper, the electron-spin resonance method is taken as the relatively most accurate method, because it can be applied directly to fossil bones and teeth over a wide range of ages.
Note: many textbooks regard radiometric methods as the most reliable, so this question is debatable.
The radio-carbon ($^{14}C$) method is used for fossils up to about 50,000 years old; the potassium-argon and uranium-lead methods are used for very old rocks (millions to billions of years), where the errors in absolute terms are large.
The electron-spin resonance (ESR) method measures the number of trapped electrons accumulated in materials such as tooth enamel and shells due to natural radiation since burial.
According to the answer key of this paper, the electron-spin resonance method is taken as the relatively most accurate method, because it can be applied directly to fossil bones and teeth over a wide range of ages.
Note: many textbooks regard radiometric methods as the most reliable, so this question is debatable.