What is relative dating?
Take a look at the definition of "dating" on the right: http://www.onelook.com/?w=dating&ls=a
Now read through the definitions linked under Science here: http://www.onelook.com/?w=relative+dating&ls=a
What do you think?
Relative dating is a method used to determine the age of fossils, rocks, or artifacts in relation to other objects or events, without necessarily assigning a specific numerical age. It provides a relative order of events or objects based on their position in the Earth's geologic record.
To understand relative dating, you need to consider a few principles:
1. Law of Superposition: This principle states that in undisturbed rock layers, the oldest rocks are found at the bottom, while the youngest rocks are found at the top.
2. Principle of Original Horizontality: This principle states that sedimentary rocks are usually deposited in horizontal layers. Any deviation from horizontal indicates a disturbance occurred after the layers were formed.
3. Principle of Lateral Continuity: This principle states that layers of sediment extend in all directions until they thin out or hit a barrier, such as a mountain or a lake.
4. Principle of Cross-Cutting Relationships: This principle states that if a rock layer or feature cuts across another rock layer, it must be younger than the rock it cuts.
By analyzing these principles and observing the relationships between different rock layers or artifacts, scientists can determine their relative ages. For example, if a layer of sedimentary rock contains fossils of an extinct species, it can be inferred that the layer is older than another layer without those fossils.
Relative dating does not provide an exact age but helps establish a chronological sequence of events. To obtain numerical ages, scientists often combine relative dating with methods like radiometric dating, which uses the decay of radioactive isotopes to determine absolute ages.