Dating in paleontology
Paleontologists frequently work in conjunction with other scientists utilizing any number of other geochronology methods.Like fossils, the chemical and physical characteristics of rocks, minerals, and organic materials can be used for correlation.
Paleomagnetic dating is based on correlation of measurements derived from oriented samples to established records of variations of the Earth's magnetic field through time.Great volcanic eruptions in the Western United States in the geologic past produced airfall deposits that have been recognized as far away as the East Coast.The USGS maintains a tephrochronology laboratory in Menlo Park, CA.Tradition paleontological and biostratigraphic correlation methods are still perhaps the most common relative dating methods used by geologists.More modern correlation technologies include use of marine stable isotope records, paleomagnetic dating, tephrachronology, geomorphological methods, sedimentation characteristics, and other geochemical and radiometric methods.The Sr geochronology method involves extracting these isotopes from fossil shell material (only several milligrams of sample are necessary for X-ray fluorescence spectroscopy).
The ratio of these two isotopes derived from a sample is compared with a database of known samples to determine relative ages.
Paleomagnetism can be used in conjunction with other correlation or dating methods to establish the age or rocks or to decipher changes in a rock's orientation through time.
In Menlo Park, contact: Dwayne Champion for more information about the paleomagnetic lab.
New dating methods are invented all the time, however, most have practical limitations.
Geologic research and mapping requires the determinations of the ages and composition of rocks.
Geochronology is the science of dating and determining the time sequence of events in the history of the Earth.