Using relative dating what can geologists determine
Radioisotopes are the best method for determining absolute age, except when dates are chiseled in manufactured rock by reliable sources for which there is a well established provenance.The absolute dates given by radioisotope dating generally agree quite well with the relative dates established through stratigraphy--as expected.Suppose you find a fossil at one place that cannot be dated using absolute methods.That fossil species may have been dated somewhere else, so you can match them and say that your fossil has a similar age.Students begin by observing a photograph and a diagram of rock layers near Whanganui, watch an animation about how the layers were formed, then use an interactive labelling diagram to work out the order in which the rocks were created.The activity offers literacy opportunities as well as practice using the science capability 'Interpret representations'.Different species of ammonites lived at different times within the Mesozoic, so identifying a fossil species can help narrow down when a rock was formed.
Organic material from the rock is tested to determine the ratio of two different types of carbon, and use that information to calculate the estimated age.
Some of the most useful fossils for dating purposes are very small ones.
For example, microscopic dinoflagellates have been studied and dated in great detail around the world.
It is difficult to determine the absolute age of a sedimentary rock because sedimentary rocks are made up of diverse particles that are all different ages.
As a result radioactive dating can only determine the age of the particles, not the whole rock.Relative dating does not provide actual numerical dates for the rocks.