• Question: How does dissolving a rock in acid tell you how old it is ?

    Asked by star49dap to Danny on 4 Nov 2020.
    • Photo: Danny Hnatyshin

      Danny Hnatyshin answered on 4 Nov 2020:

      So to figure out the age of the rock we have to do special analyses. The instruments we use do not allow you to just put a rock in the machine. Therefore you need to turn the rock into solution/liquid form. That’s where the acids come in, they dissolve the rock so you can analyze it with the instruments.

      What we are actually trying to measure is how much radioactivity is in the rock. All rocks have radioactive particles in them when they form. We know from physics that the radioactivity go away with time. So old rocks have lower radioactivity compared to the same rock that isn’t as old. The details are a bit more complicated, but that’s the basic idea!

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