Transcript Absolute and Relative Dating

Absolute and Relative Dating
• Absolute Dating – attempts to find out
approximately how old something is. Radio
isotope dating, such as carbon dating is an
example of this.
• Relatively Dating – attempts to place objects
or strata in order of oldest to youngest. This is
usually done by identifying the strata objects
are found in. Young strata are closer to the
surface, older are deeper down.
Radio isotope dating
• Radioactive elements decay into lighter elements
at a regular rate.
• The time it takes for half the atoms of a sample
of a radioactive element to decay is called its Half
Life.
• Radioisotope dating relies on measuring the ratio
of a radioactive element and its break down
products and using this measurement to
measure the age.
• It is necessary to know what isotope ratios occur
in nature so you can make a comparison.
Potassium-argon dating method
• Main article: Potassium-argon
• This involves decay of potassium-40 to argon40. Potassium-40 has a half-life of 1.3 billion
years, and so this method is applicable to the
oldest rocks.