any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product.
A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it.
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Radioactive isotopes of radium, thorium, and uranium, for example, are found naturally in rocks and soil.
Uranium and thorium also occur in trace amounts in water.
Grasses in temperate environments (barley, rice, wheat, rye and oats, plus sunflower, potato, tomatoes, peanuts, cotton, sugar beet, and most trees and their nuts/fruits, roses and Kentucky bluegrass) follow a C3 photosynthetic pathway that will yield δ In contrast, C4 feeders will have bone collagen with a value of −7.5‰ and apatite value of −0.5‰.
In actual case studies, millet and maize eaters can easily be distinguished from rice and wheat eaters.
C was originally mostly incorporated into the seawater from the atmosphere.
If the oceans the plankton live in are stratified (meaning that there are layers of warm water near the top, and colder water deeper down) the surface water does not mix with deeper waters very much, so that when the plankton dies it sinks and takes away Stable carbon isotopes in carbon dioxide are utilized differentially by plants during photosynthesis.
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The amount of the isotope in the object is compared to the amount of the isotope's decay products.