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Radioactive dating radiometric

Huxley, attacked Thomson's calculations, suggesting they appeared precise in themselves but were based on faulty assumptions.

In 1895 John Perry challenged Kelvin's figure on the basis of his assumptions on conductivity, and Oliver Heaviside entered the dialogue, considering it "a vehicle to display the ability of his operator method to solve problems of astonishing complexity." Other scientists backed up Thomson's figures. Darwin, proposed that Earth and Moon had broken apart in their early days when they were both molten.Following the development of radiometric age-dating in the early 20th century, measurements of lead in uranium-rich minerals showed that some were in excess of a billion years old.giving a lower limit for the age of the solar system.Their values were consistent with Thomson's calculations.However, they assumed that the Sun was only glowing from the heat of its gravitational contraction.These layers often contained fossilized remains of unknown creatures, leading some to interpret a progression of organisms from layer to layer.In the mid-18th century, the naturalist Mikhail Lomonosov suggested that Earth had been created separately from, and several hundred thousand years before, the rest of the universe. In 1779 the Comte du Buffon tried to obtain a value for the age of Earth using an experiment: He created a small globe that resembled Earth in composition and then measured its rate of cooling.It is hypothesised that the accretion of Earth began soon after the formation of the calcium-aluminium-rich inclusions and the meteorites.Because the exact amount of time this accretion process took is not yet known, and the predictions from different accretion models range from a few million up to about 100 million years, the exact age of Earth is difficult to determine.By their chemical nature, rock minerals contain certain elements and not others; but in rocks containing radioactive isotopes, the process of radioactive decay generates exotic elements over time.By measuring the concentration of the stable end product of the decay, coupled with knowledge of the half life and initial concentration of the decaying element, the age of the rock can be calculated.

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