Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.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.That’s because zircon is super tough – it resists weathering. Each radioactive isotope works best for particular applications.The half-life of carbon 14, for example, is 5,730 years.Relative dating is a dating method that used to determine determine the relative ages of geologic strata, artifacts, historical events, etc.This technique does not give specific ages to items.It’s based either on fossils which are recognized to represent a particular interval of time, or on radioactive decay of specific isotopes. Based on the Rule of Superposition, certain organisms clearly lived before others, during certain geologic times.After all, a dinosaur wouldn’t be caught dead next to a trilobite.Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.