Start How do relative and radioactive dating work

How do relative and radioactive dating work

The results showed that Ötzi died over 5000 years ago, sometime between 33 BC. Uranium has a very long half-life and so by measuring how much uranium is left in a rock its approximate age can be worked out.

For inorganic materials, such as rocks containing the radioactive isotope rubidium, the amount of the isotope in the object is compared to the amount of the isotope's decay products (in this case strontium).

The object's approximate age can then be figured out using the known rate of decay of the isotope.

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.

This age is computed under the assumption that the parent substance (say, uranium) gradually decays to the daughter substance (say, lead), so the higher the ratio of lead to uranium, the older the rock must be.

These skeptics do not provide scientific evidence for their views.

Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data.

The carbon-14 it contained at the time of death decays over a long period of time.

By measuring the amount of carbon-14 left in dead organic material the approximate time since it died can be worked out.

The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them: Fossil sequences were recognized and established in their broad outlines long before Charles Darwin had even thought of evolution.

Early geologists, in the 1700s and 1800s, noticed how fossils seemed to occur in sequences: certain assemblages of fossils were always found below other assemblages. Since 1859, paleontologists, or fossil experts, have searched the world for fossils.

In the past 150 years they have not found any fossils that Darwin would not have expected.