How to use absolute dating

A layer that is higher is of later age than a layer that is lower in order.This means that the oldest are the strata that are lying at the bottom.Dendochronology This method of dating is based on the number, width, and density of annual growth rings of long-lived trees.A master tree-ring index has been constructed in the southwestern United States for the Douglas fir and bristlecone pine.Obsidian Hydration Dating This method is used to calculate ages in years by determining the thickness of rims (hydration rinds) produced by water vapor slowly diffusing into freshly chipped surfaces on artifacts made of obsidian or recent volcanic glass.

Counting and correlation of varves have been used to measure the age of Pleistocene glacial deposits.However, age of deposition does not mean the age of artifacts found in that layer.Artifacts found in a layer can be compared with other items found in layers of similar age and placed in order.Thermo Luminescence (TL) Dating This method is based on the phenomenon of natural ionizing radiation inducing free electrons in a mineral that can be trapped in defects of the mineral’s crystal lattice structure.When trapped electrons escape as TL and are heated to a temperature below incandescence, the TL of a mineral such as quartz, can be recorded.

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