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How Earth Formed

The Big Bang, early changes to the earth's atmosphere, and the development of oxygen on our planet.

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How Old Are Rocks?

How Old Are Rocks?

Zircon containing rocks. image courtesy of Ryan Somma

Not As Old As Zircons

How old is the Earth? Well, it must be at least as old as the oldest rock. That sounds reasonable, but are rocks the oldest things around? As a matter of fact, no! Those would be zircons, and they are changing people's view of our planet.

No Duh's and Head Scratchers


  1. What characteristic of zircons make them excellent sources of information about the early Earth? How common is this trait among minerals?
  2. Are you surprised that zircons have rings like trees? Why or why not? How are these rings key to the usefulness of zircons? What does it say about the processes acting on zircons?
  3. How is information from zircons changing views of the conditions of early Earth? How does this information compare to what you have previously heard about conditions on the early Earth? Does this information change your view with regards to how the Earth formed? What implications do these new findings have regarding the origin of life?
  4. In science, do you think people should be cautious about expressing ideas with limited information? Why or why not? Remember, peer vetting of ideas is an important part of the scientific process.
  5. What happens sometimes with ideas that people really like, but have limited information about? Can you think of a way to improve this situation? Do you think scientists are more or less susceptible to bias than non-scientists?
  6. Ask your parents or a relative about conditions of the early Earth. Is their response consistent with these new findings? Why is it important to constantly reevaluate old theories as new information comes in? How does this make you feel in general about hypotheses that are heavy on thinking but light on evidence?


Fancy some zircon hunting? image courtesy of Ryan Somma

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