Description of absolute dating and numerical age
It is important to realize that with new information about subdivision or correlation of relative time, or new measurements of absolute time, the dates applied to the time scale can and do change.
Revisions to the relative time scale have occurred since the late 1700s.
Absolute dating places events or rocks at a specific time.
If a geologist claims to be younger than his or her co-worker, that is a relative age.
Since relative dating can easily be verified by superposition (the younger bed over the older one), intrusion (the intrusive being younger than the intrusive rock), and use of index fossils (younger fossils in a rock layer make that layer younger than another containing older fossils), relative dating can be confirmed right at the field using one's direct observation.