RELATIVE AND ABSOLUTE DATING

11
RELATIVE AND ABSOLUTE DATING Ashley Allen Oneonta High School Alabama Paleontological Society

description

RELATIVE AND ABSOLUTE DATING. Ashley Allen Oneonta High School Alabama Paleontological Society. Objectives. Distinguish between absolute dating and relative dating. Review law of superposition. Discuss the importance of half-life and radioactive decay. - PowerPoint PPT Presentation

Transcript of RELATIVE AND ABSOLUTE DATING

Page 1: RELATIVE AND ABSOLUTE DATING

RELATIVE AND ABSOLUTE DATING

Ashley AllenOneonta High School

Alabama Paleontological Society

Page 2: RELATIVE AND ABSOLUTE DATING

ObjectivesDistinguish between absolute dating and relative dating.Review law of superposition.Discuss the importance of half-life and radioactive decay.Conduct activity on relative and absolute dating.

Page 3: RELATIVE AND ABSOLUTE DATING

Two Ways to Skin a CatRelative dating of fossils is a system in which a fossil is given an age designation in terms of epoch, period, or era which can be compared to other geologic units of time as older or younger, but without the burden of assigning a specific number. For example, a Pennsylvanian lycopod bark impression is older

than a Cretaceous oyster and younger than a Mississippian brachiopod

Relative dating is best explained when covering the law of superposition and a geologic time scale

Absolute dating of a fossil involves assigning a specific quantity of age with a fossil such as saying that an echinoid, Hardouinia bassleri, is 83 million years old.

Page 4: RELATIVE AND ABSOLUTE DATING

Two Inescapable LawsThe law of superposition states that older sedimentary rocks were deposited prior to younger sedimentary rocks, therefore, as one ascends a rock face with multiple formations, the oldest rock layer is on the bottom and the rock units get progressively younger as one ascends the exposure.The law of faunal succession states that as one views progressively older fossils, they become more and more dissimilar with modern forms of life with which we are most familiar.

Page 5: RELATIVE AND ABSOLUTE DATING

Law of Superposition

Page 6: RELATIVE AND ABSOLUTE DATING

Law of Faunal Succession

Note the general appearance of more familiar species the closer one gets to the present time.

Page 7: RELATIVE AND ABSOLUTE DATING

Radioactive DecayUnstable parent radioactive isotopes decay at a stable rate which cannot be altered.Each type of radioactive parent isotope has a unique half-life.A half-life is the amount of time that it takes for half of the given radioactive parent isotope to decay into a stable daughter product.By comparing the amount of radioactive parent isotope in remains to the stable daughter product, an absolute age may be determined.

Page 8: RELATIVE AND ABSOLUTE DATING
Page 9: RELATIVE AND ABSOLUTE DATING

Carbon Dating

Page 10: RELATIVE AND ABSOLUTE DATING

Web ResourcesMany radiometric dating activities may be found by going to http://www.kn.pacbell.com/wired/fil/ or by typing filamentality into any search engine.At the core of each activity is the concept of half-life.Technology will limit the amount of detectable radioactive parent isotope or stable daughter product.

Page 11: RELATIVE AND ABSOLUTE DATING

ReferencesLaw of Superposition - http://www.calstatela.edu/faculty/acolvil/geotime/grandcanyon_strat.jpgLaw of Faunal Succession - http://mpschmidt.homestead.com/files/GeoTimeScale.jpgCarbon Dating - http://ttevisual.com/physics/images/file5/dkph5.09-3_212.jpgCarbon Dating Shell - http://www.fmi.uni-sofia.bg/fmi/contmech/kmarkov/history/gifs/carbon.gif