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Measuring Age of Artifacts and Fossils

By Unknown - February 18, 2018

In geological time scale there is a geological period that is fanerozoikum, arkeozoikum, and proterozoikum. Archeozoic means ancient life time, this time is the beginning of the formation of the earth's crust then develop into protokontinen. In addition there Proterozoic which is the initial geological period of the formation of hydrosphere and atmosphere. In this day and age began to develop from single-celled organisms to many-celled. These two epochs are known as pre-Cambrian times. Then last there is Fenerozoikum which means there is a real life. For Fenerozoikum itself is divided into 3 ages, namely Paleozoikum (old, ancient), Mesozoikum (middle time), and Kenozoikum.




One time the archaeologists found the bone benulang, the remnants of plants and fossil-dirt. The remaining DNA indicates they are from humans but not their age. To that end, scientists look to the carbon contained in the ancient impurities.

By definition, every atom of a given element has a certain number of protons at its core. For example the carbon element has six protons, but the number of neutrons in the nucleus can vary. This is different from the form of an element called isotops inherently stable or unstable. The unstable are called radioactive isotopes, and over time they will decay, forming particles (neutrons or protons) and energy (radiation) because they are turned into isotopes or other elements. They do this at a constant rate called the half-life (half life) isotope ".

How did the scientists determine the age of the fossils they found?

There are several methods to determine the age of fossils they find. Of the many methods available, we will describe two methods used by scientists to determine the age of fossils.

"Radiometric Dating Method", this method is a very common method performed by archaeologists. The system of this method is essentially calculating the same elemental ratio in the atmosphere to the principle of the half-life of the atomic decay, one of which is the C-14 element. This method itself was developed by Professor of Chemistry in the United States named Willard Libby in the late 1940s.


Radiometric Dating

The calculation of this method is to use the concept of isotope which is done in such a way that it will relate to the concept of half-life and carbon as a benchmark calculation. The reason for using carbon is due to the carbon questioning of 15 isotopes that mostly have very fast half-life due to their unstable isotopes. But C-14 has an isotope that has a long half-life of about 5,730 years. C-14 is formed in the atmosphere, from N-14 that reacts with radiation from outside the solar system. Meanwhile, the fossil to be sampled is usually a living thing. Then, in the presence of the carbon cycle will make all living things always in direct contact with the atmosphere, so that C-14 levels will also come into the body of all living things. When a living thing dies, its relationship will break with the carbon cycle. From this calculation to determine the age of fossils is done, that is by comparing the half-life of the C-14 levels in fossils with levels of C-14 in the atmosphere today.

For radiometic dating methods are not always based on carbon because the C-14 indicator has some limitations that can affect the calculation of fossil life. The first is the limitation of age in the calculation, usually the limit of the calculation using C-14 is 50,000 years, because the older fossil age will cause decay in C-14 more and more, so the half-life also decreases. The second reason is that the C-14 levels in the atmosphere sometimes change dramatically due to the burning of fossil fuels that do not have C-14 and will reduce C-14 levels in the atmosphere. Then there is a nuclear test that will actually menmabah level C-14 in the atmosphere to two-fold.

To overcome this, archaeologists also use other types of radiocative elements such as K-40 that decays into Ar-40 with half-life of 1.25 billion years. Because of its very long beak time, the method with K-Ar is used to calculate the age of rocks and minerals. Then there is also a Uranium element in mineral soil layer to determine the age of dinosaur fossils that are more than 65 million years old.

"Stratigraphic Method". Stratigafi is one of the geological sciences that learn about the layers of the earth, precisely the layers of rock in the outermost layer of the earth is the crust, and how the formation of these layers. This field was first researched deeply by Nicolas Steno in 1669, he made the basic theory that scientists can analyze the fossil age based on its location in different layers of soil.



Stratigraphy

This stratigraphic science essentially allows scientists to estimate the fossil life of the land where the fossil was found. There are 5 basic principles in stratigraphy that help scientists determine the age of fossils:

  1. Law of Superposition, which is the lower layer of soil where the fossil is found, the older the fossil age.
  2. Principle of Original Horizontality which essentially explains that all the deposits that make up the layers will all make the layers generally horizontal or flat, resulting from erosion.
  3. Principle of Lateral Continuity which explains that all the deposits will spread in all directions.
  4. Principle of Cross-cutting Relationships which says that if something makes a piece in one or more layers, the piece is younger. Or, in principle, if there is a cut through a certain layer, it means that the piece occurs after the layer is present.
  5. Principle of Faunal Succession, this principle relates to living things that exist when a layer of soil is being formed.
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