Anthropology Answer Writing Practice 2018 - Week 3 - Question 1
90 Days Anthropology Answer Writing Practice Question 1 for 26-Nov-2018
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26-Nov-2018 - Question 1
Discuss absolute and relative dating methods. 200 words
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Archaeological anthropologist use dating methods to place fossil evidence, ancient remains and objects into a geological timeline.
There are two types of dating methods
Absolute dating methods.
Relative dating methods.
Absolute methods are also known as chronometric methods. These methods reveal age in calendar years, though not an exact date but a range of years. Due to this fact, the nomenclature has been changed. Now, absolute methods are called chronometric methods. These methods use physical and chemical ways to estimate age.
Relative methods reveal temporal order of the event, object etc. It means they tell us whether a particular event occurred before or after another event.
It is very important to select a particular method to find out the age of a particular type of remains, fossils etc. For instance, radiocarbon methods reveal the age of organic materials effectively. Electron spin resonance methods effectively reveal ages of bony hard materials like coral, bones, teeth, shells etc. There are many methods which have limitations. Not each method is capable of revealing dates for very old fossils, say, Miocene age. Hence, selection of dating methods is very crucial.
Here, we are discussing two methods.
The Lead method. It was discovered by Boltwood in 1907. The working principle of this method is based upon the fact that Uranium-238 disintegrates to produce Lead with an atomic weight of 206 plus Helium. It is estimated that with any definite amount of uranium, one half of it will break down into Lead in course of 450 crore years. This is known as the half-life of uranium which is independent of the initial amount. This method has a limitation that uranium is not a common element to be found frequently in fossil samples.
Palaeomagnetism. The Working of this method is based upon the fact that the magnetic field of earth reverses periodically in a direction as well as intensity. The magnetic field (its charged particles) of the contemporary time gets trapped in the material when they consolidate into rocks.
Similarly, you can prepare notes on other dating methods like radiocarbon methods, fission track method, K-Ar method, electron spin resonance method, uranium method, chemiluminescence, thermoluminescence, optically stimulated luminescence.