* Stratification: Rocks form in layers, with older layers typically found beneath younger layers. This is called the principle of superposition.
* Fossil Correlation: Fossils are often used as "time markers" because they represent organisms that lived during a specific geological period. Finding the same fossils in different locations helps scientists correlate rock layers across vast distances.
* Exceptions: There are exceptions to this rule. Some fossils may be "reworked," meaning they were eroded from older layers and deposited in younger ones. Also, geological events like faulting can disrupt the original order of layers.
In summary: Fossils in the same strata are generally assumed to be from the same age, but it's important to consider potential exceptions and the broader geological context.
