Principles of relative dating of geologic events
organisms, geologists employ a variety of techniques.These include some that establish a relative chronology in which occurrences can be placed in the correct sequence relative to one another or to some known succession of events.This is the same principle used to determine relative age in the trash pits discussed previously.In fact, sedimentary rocks are, in a sense, trash from the Earth's surface deposited in basins.The clasts (in the bed above the unconformity) are derived from the underlying (older) bed.
Thus, in a sequence of layers that have not been overturned by a later deformational event, the oldest layers will be on the bottom.
Rock layers extend continuously in all directions, until they thin out at the edge of the depositional basin, or grade into a different type of sediment.
Discussed by English geologist Sir Charles Lyell, 1830s.
These are often characterised as the norm, rather than the exception.
I thought it would be useful to present an example where the geology is simple, and unsurprisingly, the method does work well, to show the quality of data that would have to be invalidated before a major revision of the geologic time scale could be accepted by conventional scientists.