For example, which is older, the bricks in a building or the building itself?Are there repairs or cracks in the sidewalk that came after the sidewalk was built?
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.To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.Geologists draw on it and other basic principles ( to determine the relative ages of rocks or features such as faults.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.
Within three weeks, there will be nothing left but a few small bones." A fossil normally preserves only a portion of an organism, usually that portion that was partially mineralized during life, such as bones and teeth.
Trace fossils are the marks left by a living organism, such as feces, footprints or impressions of feathers or leaves.
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.
Relative age dating also means paying attention to crosscutting relationships.