Relative age is the age of a rock layer (or the fossils it contains) compared to other layers. It can be determined by looking at the position of rock layers. Absolute age is the numeric age of a layer of rocks or fossils. Absolute age can be determined by using radiometric dating.
What does absolute dating determine?
Absolute dating methods determine how much time has passed since rocks formed by measuring the radioactive decay of isotopes or the effects of radiation on the crystal structure of minerals. Paleomagnetism measures the ancient orientation of the Earths magnetic field to help determine the age of rocks.
What is absolute age used for?
The absolute age of an Earth material is a measure of how old it actually is in years. Some scientists prefer to call it calendar age, because the term suggests that the age can be plotted on a calendar.
What does relative age tell us?
Relative age dating tells us which fossils are older and which fossils are younger. It does not tell us the age of the fossils. To get an age in years, we use radiometric dating of the rocks. Not every rock can be dated this way, but volcanic ash deposits are among those that can be dated.
What is the best definition of absolute age?
The geologic age of a fossil organism, rock, or geologic feature or event given in units of time, usually years. of isotopic age or radiometric age, but may also refer to ages obtained from tree rings, varves, etc.