To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating.Radiometric dating is largely done on rock that has formed from solidified lava.These long time periods are computed by measuring the ratio of daughter to parent substance in a rock and inferring an age based on this ratio.

Other useful radioisotopes for radioactive dating include Uranium -235 (half-life = 704 million years), Uranium -238 (half-life = 4.5 billion years), Thorium-232 (half-life = 14 billion years) and Rubidium-87 (half-life = 49 billion years).

The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy.

However, radioisotope dating may not work so well in the future.

Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.

­ ­As soon as a living organism dies, it stops taking in new carbon.

The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced.

Lava (properly called magma before it erupts) fills large underground chambers called magma chambers.

Most people are not aware of the many processes that take place in lava before it erupts and as it solidifies, processes that can have a tremendous influence on daughter to parent ratios.

The carbon-14 decays with its half-life of 5,700 years, while the amount of carbon-12 remains constant in the sample.