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Archaeologists use many different techniques to determine the age of a particular artifact, site, or part of a site.

Two broad categories of dating or chronometric techniques that archaeologists use are called relative and absolute dating.

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Web cam uome sex - Relative dating atmossphere

Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.

Uranium is present in many different rocks and minerals, usually in the form of uranium-238.

Instead, other methods are used to work out a fossil’s age.

These include radiometric dating of volcanic layers above or below the fossils or by comparisons to similar rocks and fossils of known ages.

Some fossils, called index fossils, are particularly useful in correlating rocks.

For a fossil to be a good index fossil, it needs to have lived during one specific time period, be easy to identify and have been abundant and found in many places. If you find ammonites in a rock in the South Island and also in a rock in the North Island, you can say that both rocks are Mesozoic.In a family like this it’s hard to tell how people are related simply by age. Early geologists had no way to determine the absolute age of a geological material.With rock units we use certain principles to tell their ages relative to each other. If they didn’t see it form, they couldn’t know if a rock was one hundred years or 100 million years old.In other words, artifacts found in the upper layers of a site will have been deposited more recently than those found in the lower layers.Cross-dating of sites, comparing geologic strata at one site with another location and extrapolating the relative ages in that manner, is still an important dating strategy used today, primarily when sites are far too old for absolute dates to have much meaning.Different methods have their own limitations, especially with regard to the age range they can measure and the substances they can date.

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