Why are unstable isotopes useful for dating rocks Videochat gratis tampa fl

11-Apr-2016 07:57

Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.As a result, the heavier isotopes react more slowly than the lighter isotopes leading to isotopic separation or fractionation between reactant and product in both physical and biological reactions.Fractionation of the heavy and light stable isotopes is important because it a) produces variation in the stable isotope ratio of different element pools and b) establishes an isotope signal that can indicate the existence or magnitude of key processes involved with elemental cycling.

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These samples are carefully cataloged and analyzed with a mass spectrometer.Half-life is the amount of time it takes for half of the parent isotopes to decay. In another 5,730 years, the organism will lose another half of the remaining C-14 isotopes.This process continues over time, with the organism losing half of the remaining C-14 isotopes each 5,730 years.Many rocks and organisms contain radioactive isotopes, such as U-235 and C-14.

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These radioactive isotopes are unstable, decaying over time at a predictable rate.

For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.