Dating in paleontology

Various methods exist differing in accuracy, cost and applicable time scale.All ordinary matter is made up of combinations of chemical elements, each with its own atomic number, indicating the number of protons in the atomic nucleus.continue to make remarkable discoveries, such as that a huge meteorite that fell in the Gulf of Mexico wiped out the dinosaurs—all except the birds, the only surviving dinosaurs."Radiometric dating" can reveal the age (often tens of millions of years) of a rock or fossil or a tiny grain of pollen by measuring how much its radioactive elements have disintegrated.Additionally, measurement in a mass spectrometer is subject to isotopic interference of other nuclides with the same mass number.Corrections may have to be performed by measuring isotopic ratios of elements which interfere with the target isotope.This transformation is accomplished by the emission of particles such as electrons (known as beta decay) or alpha particles.

The processes that form specific materials are often conveniently selective as to what elements they incorporate during their formation.

If a material that selectively rejects the daughter nuclide is heated, any daughter nuclides that have been accumulated over time will be lost through diffusion, setting the isotopic "clock" to zero.

The temperature at which this happens is known as the "blocking temperature" and is specific to a particular material.

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'paleontology.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Until the 1820s, hardly anyone even suspected that dinosaurs had ever existed.

In the years since, paleontology has sought to discover the entire history of life on earth, from the era of single-celled organisms up into the human era.

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