bind updating serial number for zones - Radiometric dating of meteorites from another solar system

Other naturalists used these hypotheses to construct a history of Earth, though their timelines were inexact as they did not know how long it took to lay down stratigraphic layers.

In 1830, geologist Charles Lyell, developing ideas found in James Hutton's works, popularized the concept that the features of Earth were in perpetual change, eroding and reforming continuously, and the rate of this change was roughly constant.

His value of 56 million years added additional evidence that Thomson was on the right track.

radiometric dating of meteorites from another solar system-55

Even more constraining were Kelvin's estimates of the age of the Sun, which were based on estimates of its thermal output and a theory that the Sun obtains its energy from gravitational collapse; Kelvin estimated that the Sun is about 20 million years old.

Geologists such as Charles Lyell had trouble accepting such a short age for Earth.

giving a lower limit for the age of the solar system.

It is hypothesised that the accretion of Earth began soon after the formation of the calcium-aluminium-rich inclusions and the meteorites.

Kelvin stuck by his estimate of 100 million years, and later reduced it to about 20 million years.

The discovery of radioactivity introduced another factor in the calculation.

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.

Thus the age of the oldest terrestrial rock gives a minimum for the age of Earth, assuming that no rock has been intact for longer than the Earth itself.

For biologists, even 100 million years seemed much too short to be plausible.

In Darwin's theory of evolution, the process of random heritable variation with cumulative selection requires great durations of time.

However, they assumed that the Sun was only glowing from the heat of its gravitational contraction.

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