Radiocarbon dating estimates can be obtained on wood, charcoal, marine and freshwater shells, bone and antler, and peat and organic-bearing sediments.
They can also be obtained from carbonate deposits such as tufa, calcite, marl, dissolved carbon dioxide, and carbonates in ocean, lake and groundwater sources.
We will deal with carbon dating first and then with the other dating methods.
Now, when I did that, I made a pretty big assumption, and some you all have touched on this in the comments on You Tube on the last video, is how do I know that this estimate I made is based on the assumption that the amount of carbon-14 in the atmosphere would have been roughly constant from when this bone was living to now?
And so the question is, is the amount of carbon-14 in the atmosphere and in the water, and in living plants and animals, is it constant?
The method was developed immediately following World War II by Willard F.
Libby and coworkers and has provided age determinations in archeology, geology, geophysics, and other branches of science.
And if it isn't constant, how do you calibrate your measurement so you can actually figure out how much carbon-14 there is relative to living plants and animals at that time?
And the way that you can make that calibration, because it turns out it isn't perfectly constant, the way that you can make that calibration, there's two ways, and I have pictures here of both of them, one is to look at tree things. And I'm told this will work up to about 10,000 years. I don't know of any 10,000 year old trees, I don't think anyone does, but maybe there's some remains of old trees.Scientists use a technique called radiometric dating to estimate the ages of rocks, fossils, and the earth.Many people have been led to believe that radiometric dating methods have proved the earth to be billions of years old.Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old.Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.In the last video, we talked about the idea that if I dug up a bone someplace, if I dug up a bone, and if I were to measure its carbon-14, and I found that it had half of the carbon-14 that I would expect to find in a living animal or plant, that I said, hey, maybe one half life has gone by, or roughly for carbon-14, one half life is 5,730 years.