Relative age dating geologic cross sections
Pretty obvious that the dike came after the rocks it cuts through, right?With absolute age dating, you get a real age in actual years.But, before that, they relied upon a different approach to first determine the sequence of important events in Earth's past: Relative age dating has to do with determining the temporal ordering of events in Earth's past.Geologists employ a handful of simple principles in relative age dating; two of the most important of these are are the principles of Just as uniformitarianism is the key underlying assumption of geology, the science's most fundamental principle is superposition, developed by Danish anatomist Nicholas Steno (1638-1686) in the 17th century.is simple, intuitive, and is the basis for relative age dating.It states that rocks positioned below other rocks are older than the rocks above.Look for “absolute” ages such as cornerstones, dates carved into fresh concrete, or dates stamped on manhole covers.Absolute age dating: Have students work alone or in pairs to find an article or paper that uses radiometric age dating.
Take students on a neighborhood walk and see what you can observe about age dates around you.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.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.