Indestructible grains, preservation in bogs and lake sediments allowed pollen experts to construct detailed sequences of past vegetation and climate.
Can yield environmental evidence as far back as 3mya`Based on observation that the annual growth rings of a few tree species vary in width according to differences in seasonal growing conditions (esp. Successful means of calibrating or correcting radiocarbon dates2.
Carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth’s atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere.
Radiocarbon present in molecules of atmospheric carbon dioxide enters the biological carbon cycle: it is absorbed from the air by green plants and then passed on to animals through the food chain.
Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.Zodiac Killer Cipher supremo Dave Oranchak very kindly bounced this nicety my way: a tiny cipher sneaked into her High School yearbook by geeky/naughty Jessica Lee, that even managed to make it onto MSN: If you’re already familiar with Notorious B. G.’s lyrical output, you’ll have a reasonable idea of what to expect. But perhaps that would have looked too obvious and have been caught before going to press. 🙂 I should also mention the Reddit commenter who thinks Lee should have done ““, to preserve all the word breaks.you have to have something outside the dating technique to assess the true age.Measure of random error and refers to how often you arrive at the same answer for repeated dates (how often would you get the same answer? The closer the clusters of multiple answers, the more precise it is.