Absolute Age of Rocks

  • View

  • Download

Embed Size (px)


Absolute Age of Rocks. Chapter 9 Section 3 Pgs. 257 - 261. Absolute Age. Age of a rock or other object in years. Determine age by using the properties of atoms. Parts of an Atom. Radioactive Decay. The process of an unstable isotope breaking down Number of protons determines the element - PowerPoint PPT Presentation


  • Absolute Age of RocksChapter 9 Section 3Pgs. 257 - 261

  • Absolute AgeAge of a rock or other object in years.

    Determine age by using the properties of atoms.

  • Parts of an Atom

  • Radioactive DecayThe process of an unstable isotope breaking downNumber of protons determines the elementNumber of neutrons determines the form or isotope

  • Beta DecayNeutron turns into a proton and electron and the electron leaves as a beta particle.

  • Alpha DecayUnstable parent isotope gives off 2 protons and neutrons in the form of an alpha particle

  • Half-LifeTime it takes for half of the atoms isotope to decay.

    Number of Half-livesParent Isotope Remaining (%)11002X325412.55Y

  • ReviewWhat is absolute age?Draw an atom and label its parts.What is radioactive decay?What is beta decay? Alpha decay?What is a half-life?

  • Radiometric AgesMeasure the ratio of parent isotope to daughter product, can find the absolute age of a rock.

  • Radiocarbon DatingCarbon-14 is used to date bones, wood, and charcoal up to 75,000 years old.Living things take in carbon from environment to build their bodies.After death, carbon-14 slowly decays.Scientists compare the amount of carbon left to the environment.

  • Rock AgesOnly igneous and metamorphic rocks can be radiometrically dated.Oldest rocks found are 3.96 billion years old.Estimate earth to be about 4.5 billion years old.

  • UniformitarianismThis principle states that whats happening on earth now also happened in the past.The present is the key to the past.Earth shaped by:Slow, everyday processesViolent, unusual events

  • ReviewWhat is radiometric age?What is radiocarbon used to date?What two types of rocks can be radiometrically dated?How old is the earth estimated to be? What is the principle of uniformatarianism?What key phrase explains this principle?