Strata dating system
Known as the "Father of English geology", Smith recognized the significance of strata or rock layering and the importance of fossil markers for correlating strata; he created the first geologic map of England.
Other influential applications of stratigraphy in the early 19th century were by Georges Cuvier and Alexandre Brongniart, who studied the geology of the region around Paris.
Geologists have studied the order in which fossils appeared and disappeared through time and rocks. Fossils can help to match rocks of the same age, even when you find those rocks a long way apart.
This matching process is called correlation, which has been an important process in constructing geological timescales.
Fossils are used to determine the order and dates of the strata in which they are found.
But the fossil order itself is based on the order of strata and the assumption of evolution.
Relative dating is used to arrange geological events, and the rocks they leave behind, in a sequence.
The method of reading the order is called stratigraphy (layers of rock are called strata).
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.These variations provide a lithostratigraphy or lithologic stratigraphy of the rock unit.Chronological dating, or simply dating, is the process of attributing to an object or event a date in the past, allowing such object or event to be located in a previously established chronology.Relative dating methods are unable to determine the absolute age of an object or event, but can determine the impossibility of a particular event happening before or after another event of which the absolute date is well known.In this relative dating method, Latin terms ante quem and post quem are usually used to indicate both the oldest and the most recent possible moments when an event occurred or an artifact was left in a stratum.