Who discovered potassium argon dating

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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.By following this assumption, archaeologists can place the materials collected from the various strata into a rough chronological sequence.If archaeologists digging in an undated site find a distinctive type of pottery for which the date is known, they may conclude that the other materials found in the site along with the pottery bear the same date as the pottery.This is an example of a relative-dating technique called cross dating.Similarly, archaeologists may assign a date to an artifact based on the geologic region or strat with which the artifact is associated., dated from the same time as mammoth bones found with it because both had accumulated the same proportions of fluorine. None of them is as accurate as the absolute-dating methods, however, because the assumptions on which many relative-dating techniques are based can be misleading.

It is never the case for anthropological archaeologists, who study prehistoric materials. , confirmed that his carbon-14 test dating method was scientifically dependable within an acceptable margin of error for objects already dated. Culture History theoretical school of thought in archaeology.

For example, it is known that superbison became extinct in the Great Plains of what is now the United States and were replaced by modern bison.

Thus if archaeologists discover one site in which Folsom fluted points (the distinctive tips of a kind of prehistoric man-made weapon) are found imbedded in superbison remains, and they discover a second site in which a different kind of points, called Bajada points, are sticking in the remains of modern bison, they may conclude that Folsom points were made before Bajada points.

One of the best-known and most valuable techniques is radiocarbon dating (also called radioactive carbon dating, carbon dating, and carbon-14 dating).

All living things contain small amounts of carbon-14, a radioactive form of carbon.

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