What process gives us absolute dating of rocks
As we learned in the previous lesson, index fossils and superposition are effective methods of determining the relative age of objects.In other words, you can use superposition to tell you that one rock layer is older than another.Thomson's calculations, however, were soon shown to be flawed when radioactivity was discovered in 1896.
Several other processes result in the accumulation of distinct yearly layers that can be used for dating.
But determining the absolute age of a substance (its age in years) is a much greater challenge.
To accomplish this, scientists use a variety of evidence, from tree rings to the amounts of radioactive materials in a rock.
Each dark band represents a winter; by counting rings it is possible to find the age of the tree (Figure 11.22).
The width of a series of growth rings can give clues to past climates and various disruptions such as forest fires.