These laws of relative dating are
The most obvious feature of sedimentary rock is its layering.This feature is produced by changes in deposition over time.Relative time places events or formations in order based on their position within the rock record relative to one another using six principles of relative dating.Relative time can not determine the actual year a material was deposited or how long deposition lasted; it simply tell us which events came first.Using this process geologists are able to assign actual ages with known degrees of error to specific geologic events.By combining knowledge gained using both relative and absolute dating processes geologists have been able to produce the geologic time scale.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.
Although there might be some mineral differences due to the difference in source rock, most sedimentary rock deposited year after year look very similar to one another.
Unlike relative time, absolute time assigns specific ages to events or formations and is typically recorded in years before present.
This process requires much more sophisticated chemical analysis and, although other processes have been developed, often utilizes the decay rates of radioactive isotopes to determine the age of a given material.
This process lead to a system of time containing eons, eras, periods, and epochs all determined by their position in the rock record.
For example, rocks of the Phanerozoic eon are found on top of rocks from the Proterozoic eons therefore rocks of the Phanerozoic are younger than rocks of the Proterozoic.