Radiometric dating vs radioactive dating
Each element is made up of atoms, and within each atom is a central particle called a nucleus.Within the nucleus, we find neutrons and protons; but for now, let's just focus on the neutrons.So in order to 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.Clearly, Sedimentary Rocks A were deposited and deformed before the Volcanic Dyke intruded them.These were then eroded and Sedimentary Rocks B were deposited.Elements occur naturally in the earth, and they can tell us a lot about our Earth's past.
Radioactive dating uses the ratios of isotopes and their specific decay products to determine the ages of rocks, fossils and other substances.From the mapped field relationships, it is a simple matter to work out a geological cross-section and the relative timing of the geologic events.His geological cross-section may look something like Figure 2.The 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. 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.
So, we have a “clock” which starts ticking the moment something dies.