Radiometric dating geology
Unlike people, you can’t really guess the age of a rock from looking at it.Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.
It might be possible to date some chemical sedimentary rocks isotopically, but there are no useful isotopes that can be used on old chemical sedimentary rocks.It is also based on the premise that when the atoms of an element decay within a mineral or a rock, they stay there and don’t escape to the surrounding rock, water, or air.One of the isotope pairs widely used in geology is the decay of K is a radioactive isotope of potassium that is present in very small amounts in all minerals that have potassium in them.Radiocarbon dating can be used on sediments or sedimentary rocks that contain carbon, but it cannot be used on materials older than about 60 ka.K proportion of 0.95, which is equivalent to an age of approximately 96 Ma.