At what age range is radiocarbon dating most effective
The beauty, improvisation and simplicity of building a structure made from locally available stone, and nothing else, by arranging the stones in a particular pattern so that they lock themselves together to create a solid structure that can last for hundreds of years, is shared by many; certainly judging by the amount of Royal Horticultural Society medals that have been won in show gardens recently where dry stone walling has been a key feature.
Many birds too, such as the robin, wheatear and redstart, and the occasional small owl, have been known to occupy larger gaps, with mosses, lichens and ferns favouring the outside of the walls.From diamonds to nanotubes to DNA, carbon is indispensable for constructing practically all of the most intricate structures we know of.Most of the carbon in our world comes from long-dead stars, in the form of Carbon-12: carbon atoms containing six neutrons in their nucleus.About 1.1% of all carbon is Carbon-13, with one extra neutron.But there is another form of carbon that, while not at all abundant, is definitely worth talking about.From across the galaxy and across the Universe, from stars (including our Sun), pulsars, black holes and more, space is flooded with high-energy particles known as cosmic rays.
Most frequently, cosmic rays are protons, but a handful are heavier ions and a few are even humble electrons.
As far as we can tell, the levels of carbon-14 throughout the world have remained roughly constant throughout the past few millenia, so that when an organism dies and the carbon-14 decays, we can measure how long ago it became deceased by measuring the ratio of carbon-14 to its normal carbon-12.
The only major fluctuation we know of occurred when we began detonating nuclear weapons in the open air, back in the mid-20th Century.
I vaguely recollect asking my mother lots of other related questions, such as how the walls managed to stand up what with all the gaps in them, where all the stone came from to build them, who built them, and why they were built in the first place.
The fact they were built a long, long time ago, and the animals and plants made the wall their home, or used them as hiding places from predators, was about all I remember from my early questions.
, and is so rare that only one-in-a-trillion carbon atoms are carbon-14.