Visit the following site and read about each of Steno's laws (principles).
Nonetheless, how geologists determine the age of rocks is a mystery to many members of the public, and even to many park rangers [see Photo 2], guides, and others who share the canyon’s geologic story with others.
We do this all the time in our regular day to day lives.
For example, lets put the following movies in order of relative age from oldest to youngest: Twilight, Finding Nemo, the Avengers, the Hunger Games.
By carefully digging, we have found that each trash pit shows a sequence of layers.
Although the types of trash in each pit is quite variable, each layer has a distinctive kind of trash that distinguishes it from other layers in the pits.
We don't need to know what year any of these movies came out to place them in order of relative age.
Nemo is the oldest, followed by Twilight, Hunger Games, and the Avengers Again, we have not stated anything about the actual age of these movies, we've just put them in order relative to one another.
While this may sound questionable at first, keep in mind that we also accept the Law of Gravity with out direct proof.Relative dating permits to evaluate which one of two events is the older and, with a certain accuracy, the time difference between the two.However, will not place the examined time bracket in a general timeframe.The same thing can be done with geologic features in a rock outcrop.To do this geologists use the Laws of Relative Dating.The same questions arise for the other rock units at Grand Canyon.