Radiocarbon dating ams spung the dating game
The Radiocarbon Revolution Since its development by Willard Libby in the 1940s, radiocarbon (14C) dating has become one of the most essential tools in archaeology.
Given relatively pristine circumstances, a radiocarbon lab can measure the amount of radiocarbon accurately in a dead organism for as long as 50,000 years ago; after that, there's not enough C14 left to measure. Carbon in the atmosphere fluctuates with the strength of earth's magnetic field and solar activity.
Shy of a date stamp on an object, it is still the best and most accurate of dating techniques devised.
All living things exchange the gas Carbon 14 (C14) with the atmosphere around them—animals and plants exchange Carbon 14 with the atmosphere, fish and corals exchange carbon with dissolved C14 in the water.
Int Cal combines and reinforces data from tree-rings, ice-cores, tephra, corals, and speleothems to come up with a significantly improved calibration set for c14 dates between 12,000 and 50,000 years ago.
The latest curves were ratified at the 21st International Radiocarbon Conference in July of 2012.
You have to know what the atmospheric carbon level (the radiocarbon 'reservoir') was like at the time of an organism's death, in order to be able to calculate how much time has passed since the organism died.