1 / 9

The Fossil Record

The Fossil Record. There are two major ways of dating objects or fossils: Relative Dating Absolute Dating. How old is that fossil?. How old is that fossil?. Relative Dating Uses the relative position of fossils for age comparison. Relative Dating.

hansene
Download Presentation

The Fossil Record

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Fossil Record

  2. There are two major ways of dating objects or fossils: Relative Dating Absolute Dating How old is that fossil?

  3. How old is that fossil? • Relative Dating • Uses the relative position of fossils for age comparison

  4. Relative Dating • Cannot be used to determine the actual age of a fossil • Can only be used to compare fossil age Example: When archaeologists measure the fluorine content in bones. Fluorine is from underground water. Fluorine eventually replaces other things that are in bones, so the more fluorine the bones contain the older they are.

  5. Radiometric Dating • A technique used to date materials • A comparison between the amount of a naturally occurring radioactive isotope and its decay products • Each radioactive isotope has a unique, known half-life (time for ½ of the substance to decay) • Example: Radioactive Carbon-14 has a half-life of 5730 years • The choice of dating material is based on estimated age of the artifact or fossil to be dated.

  6. Radiometric Dating • Radioactive samples decay at a predictable rate • Estimates of the original composition of a radioactive sample are made • Then the amounts of the radioisotopes present can provide a measurement of time elapsed • Example: Carbon dating, limited to organic materials • Longer lived radioisotopes in minerals are used for longer time scales • “clocks in the rocks”

  7. The amount of decay in one half-life is used to measure the time Radioactive Decay

More Related