who is dating kirsten dunst - Radioactive isotopes archaeological dating
The explanation was that the physicists had assumed that the amount of C-14 in the atmosphere had been constant, when in fact it had varied over time.
In contrast, methane made from petroleum products had no measurable radioactivity.
This discovery meant that there are three naturally occurring isotopes of carbon: Whereas carbon-12 and carbon-13 are stable isotopes, carbon-14 is unstable or radioactive.
C is created in the atmosphere by cosmic radiation and is taken up by plants and animals as long as they live.
Upon death, the isotope begins to decay and after 5730±40 years half of it is gone.
The C-14 method cannot be used on material more than about 50,000 years old because of this short half-life.
Other isotopes are used by geologists to date older material.
But as more dates became available, Egyptologists, who had hieroglyphic records back thousands of years, began to recognize that C-14 dates were generally too young.
They proved this by showing that C-14 dates of wooden artifacts with cartouches (dated royal names) did not agree.
Since tree rings provide an annual calendar, and some trees live for thousands of years, by C-14 dating the rings themselves one could correct the radiocarbon dates and calibrate the differences. should refer to the year the method was recognized, 1950.Tags: Adult Dating, affair dating, sex dating