Why is relative dating important
Often when geologists examine rock outcrops like the one illustrated above they are interested in not only the types of rocks present, but the order in which they formed.
When they put events in chronological order like they use Relative Dating.
To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.
Geologists draw on it and other basic principles ( to determine the relative ages of rocks or features such as faults.
The narrower a range of time that an animal lived, the better it is as an index of a specific time.
No bones about it, fossils are important age markers.
Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.The same thing can be done with geologic features in a rock outcrop.To do this geologists use the Laws of Relative Dating.What’s more, if the whole rock is badly weathered, it will be hard to find an intact mineral grain containing radioactive isotopes.
You might have noticed that many of the oldest age dates come from a mineral called zircon.
It’s based either on fossils which are recognized to represent a particular interval of time, or on radioactive decay of specific isotopes. Based on the Rule of Superposition, certain organisms clearly lived before others, during certain geologic times.