What is relative dating in terms of fossils
Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.Pretty obvious that the dike came after the rocks it cuts through, right?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.In a way this field, called geochronology, is some of the purest detective work earth scientists do.Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.
Unlike people, you can’t really guess the age of a rock from looking at it.This lesson is based on an online booklet that provides an introduction to the study of earth's history, published by the USGS.Using careful analogies and written historical records, the authors help students understand the development of the geologic time scale, including how this depended on gathering evidence and making comparisons.Another option would be for you to order print materials directly from the USGS.Students will likely have been introduced to the geologic time scale in earlier grades, so take this opportunity to review basic concepts and find out the extent to which they are familiar with this topic.