What is relative dating and how is it used

Posted by / 05-Aug-2017 07:43

Stratigraphy is based on the law of superposition--like a layer cake, the lowest layers must have been formed first.

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.

To answer this question requires a lot of knowledge about cars and automobile history.

If you don’t know cars you have to spend some time researching the images to find out a specific answer.

First used, and likely invented by archaeologist Sir William Flinders-Petrie in 1899, seriation (or sequence dating) is based on the idea that artifacts change over time.

Like tail fins on a Cadillac, artifact styles and characteristics change over time, coming into fashion, then fading in popularity. The standard graphical result of seriation is a series of "battleship curves," which are horizontal bars representing percentages plotted on a vertical axis.

The trade-off is that the second method gives us a more precise answer to the question of “how old is this rock? Can you place these cars is relative order from oldest to youngest?

When you think you know the answer, click on the image to see if you are right.

Seriation, on the other hand, was a stroke of genius.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.The scholar most associated with the rules of stratigraphy (or law of superposition) is probably the geologist Charles Lyell.Here is a sketch from his field notes that Darwin updated for the “On a bare gently inclined surface of the porphyritic gneiss in Botofogo Bay, I observed the appearance here represented. ) Now there are two basic ways in which geologists “date” rocks – relative dating and absolute dating.A fragment seven yards long and two in width, with angular and distinctly defined edges, composed of a peculiar variety of gneiss with dark layers of mica and garnets, is surrounded on all sides by the ordinary gneiss-granite; both having been dislocated by a granitic vein. The first method describes the way we put geologic units/events in relative order, without actually assigning them a specific (numeric) age.

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I know what you are thinking….a lot of people know that Darwin ultimately married his first cousin Emma Wedgwood.

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