How were fossils dated before radioactive dating
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.
I also like this simple exercise, a spin-off from an activity described on the USGS site above.
Take students on a neighborhood walk and see what you can observe about age dates around you.
You might have noticed that many of the oldest age dates come from a mineral called zircon.Because of this, the bones displayed in museums are covered with heavily leaded paint.Mainstream scientists explain this phenomenon by citing elemental uranium deposits in Colorado and Wyoming.These deposits were formed during the Jurassic-age.The radioactivity is generated from sandstones found in the region.