Relative age dating example


Using relative dating the fossil is compared to something for which an age is already known.For example if you have a fossil trilobite and it was found in the Wheeler Formation.This means that a quartz sandstone deposited 500 million years ago will look very similar to a quartz sandstone deposited 50 years ago.Making this processes even more difficult is the fact that due to plate tectonics some rock layers have been uplifted into mountains and eroded while others have subsided to form basins and be buried by younger sediments.The same rock formation also contains a type of trilobite that was known to live 415 to 425 million years ago.Since the rock formation contains both types of fossils the ago of the rock formation must be in the overlapping date range of 415 to 420 million years.Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.The majority of the time fossils are dated using relative dating techniques.



To deal with many of these problems geologists utilize two types of geologic time: relative time and absolute time.Using this process geologists are able to assign actual ages with known degrees of error to specific geologic events.By combining knowledge gained using both relative and absolute dating processes geologists have been able to produce the geologic time scale.The most obvious feature of sedimentary rock is its layering.

This feature is produced by changes in deposition over time.

With this in mind geologist have long known that the deeper a sedimentary rock layer is the older it is, but how old?



Relative age dating example comments


  • The Laws of Relative Dating — Mr. Mulroy's Earth Science profil de paulette60

    paulette60

    Relative Often when geologists examine rock outcrops like the one illustrated above they are interested in not only the types of rocks present, but the order in. For example, lets put the following movies in order of relative age from oldest to youngest Twilight, Finding Nemo, the Avengers, the Hunger Games.…
  • Relative Age of Rocks PPT - Rockway Middle School profil de paulette60

    paulette60

    Apr 6, 2015. Use the LAW OF SUPERPOSITION in horizontal sedimentary rock layers, the oldest layer is at the bottom. Each higher layer is younger than the layers below it. Other Clues to Relative Age. Clues from Igneous Rocks 1. Lava that hardens on the surface is called an Extrusion. example – an eruption would.…
  • DETERMINING AGE OF ROCKS AND FOSSILS profil de paulette60

    paulette60

    To use radiometric dating and the principles of determining relative age to show how ages of rocks and fossils can be narrowed even if they cannot be dated radiometrically. Return to top. For example, U-235 is an unstable isotope of uranium that has 92 protons and 143 neutrons in the nucl eus of each atom. Through a.…