Relative age dating powerpoint
Dating, in geology, determining a chronology or calendar of events in the history of Earth, using to a large degree the evidence of organic evolution in the sedimentary rocks accumulated through geologic time in marine and continental environments.
To achieve this precision, geochronologists have had to develop the ability to isolate certain high-quality minerals that can be shown to have remained closed to migration of the radioactive parent atoms they contain and the daughter atoms formed by radioactive decay over billions of years of geologic time.
In the ideal case, the geologist will discover a single rock unit with a unique collection of easily observed attributes called a marker horizon that can be found at widely spaced localities.
Any feature, including colour variations, textures, fossil content, mineralogy, or any unusual combinations of these can be used.
Similarly, in geologic studies, vast quantities of information from widely spaced outcrops have to be integrated.
Some method of correlating rock units must be found.
These include some that establish a relative chronology in which occurrences can be placed in the correct sequence relative to one another or to some known succession of events.