historical geology

Historical geology is a branch of geology focused on understanding the chronology of events in Earth's history. It reconstructs the sequence of geological events by examining the relationships between rocks, particularly sedimentary layers called strata.12

Key principles include the law of superposition, which states that in undisturbed rock sequences, the oldest layer is at the bottom and younger layers are progressively above it. Initially, geologists determined relative ages—whether one event or rock layer was older or younger than another. The development of radiometric dating methods, however, allows for the determination of numerical ages, revealing that Earth is approximately 4.6 billion years old. This field helps establish an ordered timeline of Earth's past, from its formation to the present.2