5 rules of relative dating
Throughout the history of life, different organisms have appeared, flourished and become extinct.
Many of these organisms have left their remains as fossils in sedimentary rocks.
Bring relative dating principles to life with the activity Rock layers and relative dating.
Some fossils, called index fossils, are particularly useful in correlating rocks.
For a fossil to be a good index fossil, it needs to have lived during one specific time period, be easy to identify and have been abundant and found in many places. If you find ammonites in a rock in the South Island and also in a rock in the North Island, you can say that both rocks are Mesozoic.
So we can infer that coal seam is younger than the faults (because it disrupts them), and of course the upper sandstone is youngest of all, because it lies on top of the coal seam.
Exercise 8.1 Cross-Cutting Relationships The outcrop shown here (at Horseshoe Bay, B. Buff/pink felsic intrusive igneous rock present as somewhat irregular masses trending from lower right to upper left 2. A 50 cm wide light-grey felsic intrusive igneous dyke extending from the lower left to the middle right – offset in several places Using the principle of cross-cutting relationships outlined above, determine the relative ages of these three rock types.