2 examples of relative dating
For purposes of relative dating this principle is used to identify faults and erosional features within the rock record.Then, by applying the Principle of Cross-Cutting we are able to relatively date those processes.The principle of cross-cutting states that any geologic feature that crosses other layers or rock must be younger then the material it cuts across.Using this principle any fault or igneous intrusion must be younger than all material it or layers it crosses.As sediment weathers and erodes from its source, and as long as it is does not encounter any physical barriers to its movement, the sediment will be deposited in all directions until it thins or fades into a different sediment type.This concept known as the Principle of Lateral Continuity allows us to assume that similar layers of rock or sediment that are separated by a valley or other erosional feature were once continuos.This follows due to the fact that sedimentary rock is produced from the gradual accumulation of sediment on the surface.
The first principle is the Principle of Superposition which states that in an undisturbed succession of sedimentary rock, the oldest layers are on the bottom.
Therefore, the piece, or inclusion, must be younger than the material it is included in. Aside from single-celled bacteria, most living organism reside at or very near the Earth's surface either in continental or oceanic environments.