Activity 8 3 absolute dating of rocks and fossils

These break down over time in a process scientists call radioactive decay.Each original isotope, called the parent, gradually decays to form a new isotope, called the daughter.

Name: Radiocarbon dating Material used: Organic remains such as wood and seeds Age range: Younger than 60,000 years ago How it works: Measures the amount of radioactive carbon-14 in the organic remains of living things Name: Fission track dating Material used: Volcanic glass, zircon and other crystals Age range: 10,000 to 500 million years ago How it works: Measures radioactivity by counting tracks left in crystals by decaying uranium atoms Name: Optically stimulated luminescence (OSL) Material used: Wind-blown sediment with lots of quartz or feldspar mineral grains Age range: Younger than 100,000 years ago How it works: Measures radiation that the mineral receives after it has been buried away from light Name: Fossil correlation Material used: Fossils Age range: All ages How it works: Fossils found in an undated rock are matched to similar fossils found in rocks that have been dated in other places Layer 1: Mudstone – sediments laid down in deep water.Fossils include the belemnite Belemnopsis aucklandica. Which dating method is best for rocks with fossils in?Layer 2: Mudstone – sediments laid down in deep water. Which dating method is best for rocks with fossils in?Layer 3: A thin layer of tephra – a rock made of the ash from a volcanic eruption.Which dating method is best for volcanic ash containing crystals of zircon?