Dating Fossils – How Are Fossils Dated?
Geologists use radiometric datingg to estimate how fossil dating ago rocks formed, and to infer the ages of fossils contained fossil dating those rocks. Radioactive elements decay Fossil dating universe is full of naturally occurring radioactive elements. Radioactive atoms are inherently unstable; over time, radioactive "parent atoms" decay into stable "daughter atoms. When molten rock cools, forming what are called igneous rocks, radioactive atoms are trapped inside. Afterwards, they decay at a predictable rate.
By measuring the quantity of unstable atoms left in a rock and comparing it to the quantity of stable daughter atoms in the rock, scientists can estimate the amount of time that has passed since that rock formed. Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks fossil dating than 50 thousand years. So in order datjng date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.
Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium. By dating these surrounding layers, they can figure out the youngest and oldest that the ddating might be; this is known as "bracketing" the age of the sedimentary layer in which the fossils occur. Read more about how radiometric dating factored into the history of evolutionary thought.
Teach your students about absolute dating: Determining age flssil rocks and fossilsa classroom activity for grades Find additional lessons, activities, videos, and articles that focus on relative and absolute dting. Home About Copyright Credits Contact Subscribe Translations Read how others have recognized the Understanding Evolution website.