Who discovered potassium argon dating
Other techniques yield absolute dates based on the thickness of the patina, or residue, that forms over time on certain stone artifacts.
One system of absolute dating, called varve dating, was developed in the early 20 th century by Gerard de Geer, a Swedish geologist.A similar absolute-dating method dendrochronology, or the dating of trees by counting their annual growth rings was first developed for archaeological purposes in the early 1900 s by the American astronomer Andrew Ellicott Douglass.If an ancient structure has wooden parts, archaeologists can compare the number and widths of the growth rings in those parts with sequences from other samples to find out when that structure was built.He noted that the mud and clay deposited by glaciers into nearby lakes sank to the lake bottom at different rates throughout the year, forming distinct layers, called varve, on the lake bottom.Because each year s layer was different, the researchers were able to establish dates for artifacts or sites associated with a specific varve.
Search for who discovered potassium argon dating:
Ideally, analysis of the materials found on a site begins in the field laboratories while excavation is still in progress.