Radiocarbon dating the earth
Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.
Recall that atoms are the basic building blocks of matter.
Organisms usually need to be covered by mud, sand, tar or some other sediment as soon as possible or frozen or dessicated (dried out) for fossilization to occur.
Fossils, by definition, are the remains or traces of organisms that lived at least 10,000 years ago.
What scavengers like vultures and hyenas leave behind, flies, ants, worms, and bacteria quickly consume.
Within three weeks, there will be nothing left but a few small bones." A fossil normally preserves only a portion of an organism, usually that portion that was partially mineralized during life, such as bones and teeth.
Trace fossils are the marks left by a living organism, such as feces, footprints or impressions of feathers or leaves.
Material older than about 50,000 years can’t be dated with radiocarbon techniques because too little of the original radioactive material remains.
Modern labs can measure samples as small as 100 mg (0.003 oz) to a precision of ±16 years (Radiocarbon Web Info) Most fossil are dated by decay of isotopes such as Uranium 235, Potassium 40, and Rubidium 87 that have much longer half-lives than carbon 14.