Chapter 29, Problem 1TE

What six principles are used in relative dating?

To determine

The six principles used in relative dating.

Answer to Problem 1TE

The six principles used in relative dating are original horizontality, superposition, cross-cutting, inclusion, lateral continuity and faunal succession.

Explanation of Solution

Relative dating is a method used to estimate rocks' age on a relative scale rather than an actual one. It is done using six principles that allow rational judgments regarding the precedence or succession of rock forms.

The principle of original horizontality takes the fact that original sediments are deposited horizontally, and any tilt in them is a result of folding or mountain formation processes and earthquakes. The principle of superposition states the fundamental law of precedence for horizontal layers wherein the older the rock, the deeper it lies. If a layer of rock form cuts through a different kind, the principle of cross-cutting is used to determine its relative age where the rock formations which cut into a different kind are considered younger compared to the rock formations which get cut. The inclusion principle is similar to cross-cutting, but instead of a layer of rock being cut into another, the principle of inclusion talks about a piece of different rock formations inside a layer of a different kind. Here the piece of rock is considered younger than the medium in which it is in. These are the four general principles.

There are other principles, such as lateral continuity, which tell about the existence of faulting, folding, and erosion that causes horizontal discontinuity or barriers between different rock types. Another important principle established by the discovery of fossils is called faunal succession, where fossils follow an irreversible time sequence.

Conclusion:

Therefore, the six principles used in relative dating are original horizontality, superposition, cross-cutting, inclusion, lateral continuity and faunal succession.