Definition of relative dating
For example, microscopic dinoflagellates have been studied and dated in great detail around the world.
Correlation with them has helped geologists date many New Zealand rocks, including those containing dinosaurs.
The principle of Uniformitarianism states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time.
A fundamental principle of geology advanced by the 18th century Scottish physician and geologist James Hutton, is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." The principle of intrusive relationships concerns crosscutting intrusions.
Methods for relative dating were developed when geology first emerged as a natural science in the 18th century.
Geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events.
Fossils are important for working out the relative ages of sedimentary rocks.
Throughout the history of life, different organisms have appeared, flourished and become extinct.
Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age (i.e. In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another.
The method of reading the order is called stratigraphy (layers of rock are called strata).
Relative dating does not provide actual numerical dates for the rocks.
Many of these organisms have left their remains as fossils in sedimentary rocks.
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.