Relative age dating images

05 Nov

Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock.When rocks are formed, small amounts of radioactive elements usually get included.Rocks also have markers that help geologists determine their age. The exact process is complex, but all you need to know is that some atoms can change into other types of atoms (for example, Carbon can change into Nitrogen) by radioactive decay.Some radioactive materials decay more quickly than others (some take less than a second while others take billions of years! If we know how fast the element decays, we can determine its age almost like reading it off the sidewalk.Sometimes only one method is possible, reducing the confidence researchers have in the results. “They’re based on ‘it’s that old because I say so,’ a popular approach by some of my older colleagues,” says Shea, laughing, “though I find I like it myself as I get more gray hair.” Kidding aside, dating a find is crucial for understanding its significance and relation to other fossils or artifacts.Methods fall into one of two categories: relative or absolute.

One way is to look at any fossils the rock may contain. When you find layers of rocks in a cliff or hillside, younger rocks are on top of older rocks.

Four separate sets of glacial/periglacial morphosystems are present at different positions in the Western Tatras starting from valley outlets to the highest cirques, which represent successive phases of deglaciation.

R-value means and 95% confidence intervals for selected Last Glacial Maximum (LGM), and Late Glacial (LG-1, LG-2 and LG-3) stages (respectively, 40.1 ± 1.1, 46 ± 0.5, 53.5 ± 1.0 and 60.5 ± 0.3) are significantly statistically different and values for each age category are comparable for the two analyzed valleys.

If any of the fossils are unique to one of the geologic time periods, then the rock was formed during that particular time period. But these two methods only give the relative age of rocks--which are younger and which are older. Or how do we know how long ago a particular group of fossilized creatures lived?

The age of a rock in years is called its absolute age.