Age Of The Earth


Earth is the third planet from the sun, on which life exists. About 29% of the earth’s surface island and the remaining 71% covered with water and ocean, lakes, rivers, waterfalls found on the earth. The polar region of the earth mostly cold and the equator region is warm. They discovered minerals about 4.3 billion years old. Researchers know that rocks are constantly being recycled because of the rock cycle, so they continue to search for data elsewhere. Since it is believed that bodies were formed in the solar system at this time, scientists analyzed lunar rocks collected during the lunar landing and even meteorites that crashed on Earth. The duration of these two instruments ranges from 4.4 to 4.5 billion.

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Fig. 1 Define the Age of Earth



There are two method to define age of the earth.

  1. Indirect method:
    • From Salinity of Ocean Water Since we all know the nature of seawater, it is a completely saline mixture (chlorite, sodium, etc.). If the amount of salt known is carried by the river in the sea in a year. Through this process, we can calculate how long it took us to accumulate the amount of salt present in the oceans, with the help of saline that can age the earth.
    • Rate of SedimentationThis includes the method of determining the total thickness of sediment deposits and dividing by the rate of sediment.
    • Rate of Cooling Land Kelvin determined the age of the earth by measuring the constant rate of heat loss from the temperature difference between the molten hot earth and its presented state.
    • Organic EvolutionInitially, organisms had a common body structure. Complications have increased over time. Humans follow the most complex structures, so by studying evolution as well, the age of the earth was determined.
  1. Radiocarbon Dating Method:

Carbon is normally present in the atmosphere in the form of gaseous compounds such as carbon dioxide and methane. Carbon-14 (14C) is a naturally occurring radioisotope that is formed from atmospheric 14N (nitrogen) by the addition of a neutron and the loss of a proton caused by cosmic rays. It is a continuous process, so more 14C is always generated in the atmosphere. Once 14C is made, it often combines with oxygen in the atmosphere to form carbon dioxide. The carbon dioxide produced in this way diffuses into the atmosphere, dissolves in the ocean, and is incorporated by plants by photosynthesis. The animals eat the plants and eventually the radiocarbon is distributed throughout the biosphere. In living organisms, the relative amount of 14C in their body is approximately the same as the concentration of 14C in the atmosphere. When the organism dies, it stops receiving 14C, so the ratio between 14C and 12C will decrease as 14C gradually breaks back to 14N. This slow process, called beta decay, releases energy through the emission of electrons from the nucleus or positrons. After approximately 5730 years, half of the initial 14C concentration will be converted back to 14N. This is referred to as its half-life or the time taken for half of the original isotope concentration to disintegrate back into its more stable form. Because the half-life of 14C is long, it is used to date earlier living objects, such as old bones or wood. By comparing the ratio of the 14C concentration found in an object to the amount of 14C in the atmosphere, the amount of an isotope that has not yet decayed can be determined. Based on this amount, the age of the material can be accurately calculated if the material is considered to be less than 50,000 years old. This technique is called radiocarbon dating or carbon dating for short.

Principle Of Radioactive Methods: A radioactive parant element decays into a stable doughter element at a constant rate.

Example- (U-238), (Potassium-40), and (Rabidium-87).

“ The age of rocks and minerals that contain radioactive isotopes is determined by measuring the accumulation of the daughter products in them, that is a procedure called Radiometric dating.

How can calculate age of earth?


fomula earth


– [logp]p = λ(t)

– [logp-logpo] = λ(t-o)

– [logp-logpo] = λt                   (λ=Decay Constant)

  loga- logb = log a/b

  log Po-log p =λt

log Po/P = λt Po/P= eλt ( that situation are not sufficient for known dating of rocks)

Radioactive dating of rocks:

P+D= Pe λt

D = Pe λt-P

Where: D= Concentartion Date of nuclie

             P= Concentration Parents nuclie           

{D= Do+p (eλt-1)} that’s delivation are suitable for dating of rocks

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