is simple, intuitive, and is the basis for relative age dating.
It states that rocks positioned below other rocks are older than the rocks above.
Through use of techniques (which were developed during the 20th century; see Section 2.2), they were able to later assign dates in years before the preset to important events in Earth's history.
With absolute age dating, you get a real age in actual years.
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.
You can see that the curb is offset: the bottom half does not line up with the top half.
As it turns out, the famous San Andreas fault runs below the curb at this location, which has caused the curb to be broken and displaced.
An imaginary cross-section, showing a series of rock layers and geological events (A-I).