Climate chronology uses evidence of a climatic change, such as an ice age, as a benchmark for dating. It does not provide a fossil's age in years. If it had happened before the layers had formed, then we wouldn't see it punching through all the layers; we would only see it going through the layers that had existed at the time that it happened. Biostratigraphy is most useful for determining geologic time during the Phanerozoic Eon Greek phaneros, "evident"; zoic, "life"the time of visible and abundant fossil life that has lasted for about the past million years. Absolute age dating:
Geologic Age Dating Explained
Concepts Deep time Geological history of Earth Geological time units.
Explore over 4, video courses. Earth Science. However, relative methods are still very useful for relating finds from the same or nearby sites with similar geological histories.