Lesson plan relative dating
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.
This is a two week learning segment on hotspot volcanoes.
This is a collaborative effort between Melanie Mc Williams, a high school Earth and Planetary Science teacher at Chula Vista High School in San Diego, California, and Jamie A.
Like the other kind of dating, geologic dating isn’t always simple.
The half-life of carbon 14, for example, is 5,730 years.On the other hand, the half-life of the isotope potassium 40 as it decays to argon is 1.26 billion years.So carbon 14 is used to date materials that aren’t that old geologically, say in the tens of thousands of years, while potassium-argon dating can be used to determine the ages of much older materials, in the millions and billions year range.Relative age dating also means paying attention to crosscutting relationships.Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.
In a way this field, called geochronology, is some of the purest detective work earth scientists do.