Dating of fossils by scientists

By dating these surrounding layers, they can figure out the youngest and oldest that the fossil might be; this is known as "bracketing" the age of the sedimentary layer in which the fossils occur.Teach your students about absolute dating: Determining age of rocks and fossils, a classroom activity for grades 9-12.

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. 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.

Fossils are generally found in sedimentary rock — not igneous rock.

Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years.

The laser dislodged radioisotopes and other relevant isotopes, which were detected and counted.

They then used these measurements to estimate an age for the bone.

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