In historical geology, the primary methods of absolute dating involve using the radioactive decay of elements trapped in rocks or minerals, including isotope systems from very young (radiocarbon dating with Radiometric dating is based on the known and constant rate of decay of radioactive isotopes into their radiogenic daughter isotopes.
Particular isotopes are suitable for different applications due to the type of atoms present in the mineral or other material and its approximate age.
Paleontology seeks to map out how life evolved across geologic time.
Strata are differentiated from each other by their different colors or compositions and are exposed in cliffs, quarries, and river banks.These rocks normally form relatively horizontal, parallel layers, with younger layers forming on top.Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation.Index fossils are fossils that are known to only occur within a very specific age range.If a fossil is found between two layers of rock whose ages are known, the fossil's age is thought to be between those two known ages.
Because rock sequences are not continuous, but may be broken up by faults or periods of erosion, it is difficult to match up rock beds that are not directly adjacent.
Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.
The majority of the time fossils are dated using relative dating techniques.
However, radioisotope dating may not work so well in the future.
Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.
The layers of sedimentary rock, or strata, can be seen as horizontal bands of differently colored or differently structured materials exposed in this cliff.