Question

Question #e8854

Answer 1

radioactive dating can only be use on igneous rocks and fossils containing Carbon less than 50,000 years old.

Explanation:

Only igneous rocks contain the radioactive elements used in most forms of radioactive dating. Petrified fossils ( those that have been turned to stone) are found in sedimentary rock formation that do not contain igneous rocks. The igneous rocks can be have been exposed to erosion that might have removed some of the parent element used to establish the ratio of the parent to daughter elements in determining the half life.

Fossils that still contain Carbon must be younger than about 50,000 years old to obtain a reliable age using Carbon 14 dating. Carbon 14 has a half life of approximately 5,700 . 57000 divided by 5700 is ten half lives. This leaves 1 part over 2 to the tenth power.

`1/ (2 xx 2 xx 2 xx 2 xx 2 xx 2 xx 2 xx 2 xx 2 xx2`) = `1/1024`

`1/1024 = .09765 %` or less than one hundredth of a percent of the original Carbon. Measuring the levels of radioactive carbon this or greater precision becomes problematic. So Carbon 14 dating is limited to relatively recent fossils.