This question has been hotly debated for over a century, especially now with the recent interest in the last Ice Age.According to established theory, sometime during the Pleistocene, around 13,000 years ago, the last great eastern ice sheet, the Laurentian, reached down only to Wisconsin and was already receding.Love-hungry teenagers and archaeologists agree: dating is hard.But while the difficulties of single life may be intractable, the challenge of determining the age of prehistoric artifacts and fossils is greatly aided by measuring certain radioactive isotopes.Though still heavily used, relative dating is now augmented by several modern dating techniques.Radiocarbon dating involves determining the age of an ancient fossil or specimen by measuring its carbon-14 content.He was employed at Caltech's Division of Geological & Planetary Sciences at the time of writing the first edition.He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.
A more recent theory propose prehistoric Solutreans of Ice Age France also sailed west to America across the Atlantic Ocean along the south ridge of the polar ice cap more than 18,000 years ago.
Carbon-14 is also passed onto the animals that eat those plants.
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.
Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide.
Green plants absorb the carbon dioxide, so the population of carbon-14 molecules is continually replenished until the plant dies.