Dating Fossils – How Are Fossils Dated?
Quantum electronics to Reasoning. In the nineteenth century, prominent scientists such agee Charles Lyell, Charles Darwin, Sir William Thomson Lord Kelvinand Thomas Huxley, were in continual debate about the age of the earth. The discovery of the radioactive properties of uranium in by Henri Becquerel subsequently revolutionized the way scientists measured the age of artifacts and supported the theory that the earth was considerably older than how is radioactive dating used to tell the age of rocks and fossils some scientists believed.
There are several methods of determining the actual or relative age of the earth's crust: However, one of the most widely used and accepted method is radioactive dating. All radioactive dating how is radioactive dating used to tell the age of rocks and fossils based on the fact that a radioactive substance, through its characteristic disintegration, eventually transmutes into a stable nuclide.
When the rate of decay of a radioactive substance is known, the age of a specimen can be determined from the relative proportions of the remaining radioactive material and the product of its decay. Inthe American chemist Bertram Boltwood demonstrated that he could determine the age of a rock containing uranium and thereby proved to the scientific fossilw that radioactive dating was a reliable method. Uranium, whose half-life is 4. Boltwood explained that by studying a rock containing uranium, one can determine the age of the rock by measuring the remaining amount of uranium and the relative amount of lead The more lead the rock contains, the older it is.
The long half-life of uranium makes it possible to date only the oldest rocks. This method is not reliable for measuring the age of rocks less than 10 million years radioactibe because so little of the uranium will have decayed within that period of time. This method is also very limited because uranium is not found in every old rock. It is rarely found in sedimentary or metamorphic rocks, and is not found in all igneous rocks.
Although the half-life of rubidium is even longer than uranium 49 billion years or 10 times the age of the earthit is useful because it can be found in almost all igneous rocks. Potassium is a very common mineral and is found in sedimentary, metamorphic, and igneous rock. Also, the half-life of potassium is only 1. Ina radioactive dating method for determining the age of organic materials, was developed by Willard Frank Libby, who received wnd Nobel Prize in Chemistry in for his radiocarbon research.
All living plants and animals contain carbonand while most of the total carbon is carbon, a very datijg amount of the total carbon is radioactive carbon Libby found that the amount of carbon remains constant in a living plant or animal and is in equilibrium with the environment, however once the organism dies, the carbon within it diminishes according to its rate of decay.
This is because living organisms utilize carbon from the environment for metabolism. Libby, and his team of researchers, measured the amount of carbon in a piece of acacia wood from an Egyptian tomb dating B. His prediction was correct. Radioactive dating is also used to study the effects of pollution on an environment. Scientists are able to study recent climactic events by measuring the amount of a specific radioactive nuclide that is known to have attached itself to certain particles that have been incorporated into the earth's surface.
For example, trll the s, when many above-ground tests of nuclear weapons occurred, the earth was littered by cesium half-life of By collecting samples of sediment, scientists are able to obtain various types of kinetic information based on the concentration of cesium found in roocks samples. Lead, a naturally occurring radionuclide with a matchmaking ukraine of Radium, a grandparent of lead, decays to radon, the radioactive gas that can be found in some basements.
Because it is a gas, radon exists rcoks the atmosphere. Radon decays to polonium, which attaches to particles in the atmosphere and is consequently rained out—falling into and traveling through streams, riversand lakes. Radioactive dating has proved to be an invaluable tool and has been used in many scientific fields, including geologyarcheology, paleoclimatology, atmospheric science, oceanographyhydrologyand biomedicine.
This method of dating has also been used to study artifacts that have received a great deal of public attention, such as the Shroud of Turin, the Dead Sea Scrolls, Egyptian tombs, and Stonehenge. Since the discovery of radioactive dating, there have been several improvements in the equipment used to measure radioactive residuals in samples. For example, with the invention of accelerator mass spectometry, scientists have been able to date samples very accurately.
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